RE: In-Ground, DE Filter Pool With Clear Green Water

We have an in-ground pool that up until recently has had very few problems. This pool is at least 30 years old but has been maintained well the whole time. We re-plastered when we moved in 8 years ago, and it probably will need to be done again next summer.

DE filter, polaris in pool vac with a boost pump. Main filter runs 4.5 hours per day.
Not super sure on the gallons, we think about 35,000 maybe, but it's irregular shaped so it's tough to get a perfect number. I suppose refilling with a meter on the hose would be the best method, can do that when we re-plaster.
About 9' deep, maybe a little more, it used to have a dive board. Auto cover, used most of the time, and a new solar heating system.

Anyway, we've been using the pucks in the floating dispensers, three dispensers and 2-3 puck each depending on the temperature and pool usage. We usually backwash 2-3 times a year, spring, couple times during summer, and sometimes one in fall.

But last year due to some personal stuff, we didn't backwash for about a year. When we back-washed at the start of the summer this year, we realized the DE filter panels needed replacing. Did that and figured we were good to go.
However, slowly we started to get green water and it's been really stubborn to get rid of. We tried upping the pucks but it didn't help, tried some powdered shock about 3 different times, it didn't work. Have not tried liquid chlorine yet.

We test with a small kit that just measures free chlorine, combined chlorine (not sure what that is) and pH. The drops are fresh, but I'm now realizing it's limited. We did find the pH too high,(we thought it was according to the test) at 7.8 and added muratic acid to lower it. It's now kinda too low at 6.8

Just tested now; Free Chlorine 0.6, Combined Chlorine between 1.0 - 0.6
pH 6.8
KH 107.4 ppm

Don't know if KH is important but I had the test kit from an aquarium so though I'd throw it in there.

Seem like it's just too low in Chlorine, but we get this low reading even after refilling all 3 floaters. It's like the chlorine is either not dissolving into the water, or maybe dissipating too quickly. I haven't used liquid chlorine.

I just ordered a new Taylor k600a test kit, so that should help me get a handle on this.

I've also read here that we should be using some kind of stabilizer, pretty sure we haven't used that at least on purpose. It may be in the chlorine pucks but I don't know.

The water is pretty clear, just green. Although since the pH has been low, there's also a slimy film on the water.

Any suggestions or ideas would be really appreciated. Thanks for listening.

Barb

Do you have steel (iron) pipes? (IMPORTANT QUESTION: Find out, if you don't know.)

Regardless, report your test results, ASAP, when you get your K2006 . . . AND do all these things:

1. Run your filter 24/7 -- on low if you have a 2 speed.
2. Add borax (20 Mule Team Borax from Walmart, etc.) 2 boxes at a time, to the skimmer. Do not CHOKE the skimmer. Test pH 4 hours later. As soon as you see the slightest pH increase, drop to 1 box at time. Stop when the pH reaches 7.2 - 7.4
3. Get some polyquat (info) ASAp and use it.
4. Maintain chlorine levels but do NOT add a large amount of chlorine at once.

Looked up KH => carbonate hardness. It's relevant info, but not in isolation.

Thanks for the reply.

I used 3/4 of a box of borax before I read your reply and got the pH up. How much I'm not sure because I got 3 different readings from 3 different tests.

Pool phenol red test-7.8 + two aquarium tests: for reg. pH-7.0; for high pH-7.4. But even the low one is better than it was. I can add the rest and get some more today, but I still won't be certain what the actual pH will be. I can see now we were kinda flying blind with such a limited test kit.

I added two gallons of 10% liquid chlorine and got the level up to 1.0. Next I added the Polyquat 60% according to the instructions. We backwashed before the borax and once more before the chlorine, but not after the Polyquat,and brushed down the sides.

We ran the pump 24hrs. after the chlorine addition, but I'm having a bit of a hard time convincing my husband to let it run that 24/7 longer than a day.

Pool temps have been about 84*F

We don't have iron pipes, they're copper or pvc with the exception of a 2' section in the filter shed.

Looks like my test kit will arrive between the 3rd and the 8th. Hopefully sooner!

We are hosting my grand nephew's 2nd birthday party on September 1st with a parent/tot swim party and really need to get this dialed in by then.

I really appreciate your time and advice!

OK. Just hold the low chlorine (1 - 3 ppm) and moderately low pH (7.0 - 7.4) and run your filter as much as you can. Dose with the polyquat ever 3 days. As soon as you get the K2006, post your results.

I hadn't realized you had a DE filter, till I inserted your signature just now. That means it's unlikely the problem is algae, since live algae stops up DE filters very quickly. With copper pipes and low pH (below 6.8), you may have very high copper in your pool water. Testing may, or may not, reveal that. If it is copper, the solution is
1. stop adding it -- keep the pH above 7, so you don't dissolve any more copper from your pipes.
2. keep it dissolved so it doesn't stain the pool -- use HEDP
3. remove it using the CuLator packs.

If it is copper, there's a good chance simply adding HEDP will turn your pool to near-blue. But even though HEDP is often marketed as a stain remover or metal remover, that is NOT what it does. HEDP just keeps dissolved metals dissolved, and helps prevent chlorine + higher pH from turning the dissolved metals into stains.

To actually REMOVE the metals, you either have to use the CuLator product (a special water-softener type material) OR you have to filter the metals out. But, to filter them, you have to precipitate them -- make them UN-dissolve, and turn them into particles . . . OR stains! The CuLator is a LOT easier, since it can 'take' the metals away from the HEDP. The downside of the CuLator is that it works slowly, and you have to use HEDP the whole time, to prevent the metals from staining.

Anyhow, you can wait till you have your test kit, so we can do some more checking to verify that it really is metals, OR you can go ahead and order both the HEDP and CuLator paks, so you have them waiting for you, and ready to use as soon as we're sure. I'll put links below, so you can go ahead, if you like.

Ben

==========================================

HEDP is a liquid phosphonate that is pretty chlorine stable, and very good at keeping dissolved metals IN the water, instead of ON your pool surfaces. It can lift recent stains, OR it can be used along with ascorbic acid, to keep the metals in the water, after the ascorbic acid is consumed by chlorine.

Jacks Magic The Pink Stuff 1qt (60% HEDP) @ Amazon
20% KemTek HEDP @ Amazon

The CuLator product is a special patented plastic material, contained in a bag that goes into the skimmer, that can slowly take metals OUT of your pool water. We think it works, and have some evidence that it does, but not proof yet. (Not likely to be available locally.)

1 ppm Culator @ Amazon
1.5 ppm Culator sold by Amazon, shipped from Periodic
4 ppm Culator sold by Amazon, shipped from Periodic
Poolmaster 16242 Poolmaster Skimmer Basket Liner @ Amazon (to protect CuLator from being damaged by scum)

OK, I put in the polyquat and brushed again and it looks like there is/was some algae growing on the surface, it came up when I brushed. So I probably have both copper and algae. Since the last backwash before the 2- 10%chlorine gallons and the polyquat, the pressure on the DE filter has risen a few points; from the 20-24psi it usually runs, to about 29psi. That happens when it's gettng clogged I think, so it may be fitering out the dead algea. We will back wash again this afternoon after the brushed algea/whatever goes thru it for a while. We are adding couple inches of water at the same time as it went down a bit with the cover off so long; it's been pretty warm the last few days.

Then after the brush, and backwash, we'll add another gallon 10% liquid chlorine and keep the filter on and shut the cover for tonight. I'll test again in the morning.

We have 32oz of Leslie's Super Metal X which according to it's MSDS sheet is 2-phosphono-1,2,4-butanetricarboxylic acid (28%). Sound similar to the HEDP you mentioned, but not exactly. Do you think this is the same thing? If not, I'll get the HEDP.

We do have some pretty bad staining on the steps and a few other places, so I wouldn't be surprised that we would have copper in the water. Also the fill line is galvinized steel and does dump rust water for the first couple gallons. We hold a bucket under it until it comes out clear, but I bet previous owners may not have done that.

Those CuLator packs sound great! I don't care if they work slowly, as long as they get rid of the metal instead of just dissolve it. I'll get some of those too.

Since the polyquat and brushing all the algae(?)stuff(?) Copper(?) or combo has made the water cloudy, but I think it will filter out. So that's my plan until I get the test kit. Thanks again for the great advice. I feel like maybe we can get a handle on this now. And I now realize how lax we have been about maintenence. We fired the pool guy three years ago cause we caught him billing for days he didn't come, and ironically we're pretty much doing the same thing up til now. That's going to change.

It looks like you need to get HEDP. I didn't realized the old Monsanta Dequest brand was still active; it's now owned by ThermPhos, and is documented at www.dequest.com. Any how, the properties I could find for Dequest 7000 (2-phosphono-1,2,4-butanetricarboxylic acid) mentions calcium scale inhibition, but not heavy metal sequestration or chelation. Usually, if a product desired property is NOT mentioned, it's not present.

Let me caution you that the stain removal process is VERY sequence dependent; do things out of order, and you can end up wasting all the chemicals you bought!!

Quote:

---

Dequest® 7000
Title : Dequest® 7000
Synonyms : 2-Phosphonobutane - 1,2,4 - tricarboxylic acid
Cas number : 37971-36-1
Einecs number : 253-733-4
Product grade : Industrial
Description : Excellent Chlorine stablity and calcium scale inhibition in high stressed alkaline conditions.
Applications : Controls scale where halogen-based biocides or hypochlorite bleach are employed. Controls calcium scale formation in high stressed alkaline conditions.
Storage : Material should be kept cool and dry for best results.
Shelf life : 2 years
Packaging : Drum; Tote; Bulk
Safety : UN 3265 CORROSIVE LIQUID, ACIDIC, ORGANIC, N.O.S., Class 8, PG III


Dequest® 2010
Title : Dequest® 2010
Synonyms : 1-Hydroxyethylidene -1,1,-diphosphonic acid, HEDP
Cas number : 2809-21-4
Einecs number : 220-552-8
Product grade : Industrial
Description : Dequest® 2010, noted for its excellent CaCO3 scale inhibition and chlorine stability is based on hydroxyl ethylidene (1, 1-diphosphonic acid) and is approved for applications in which boiler steam comes in contact with food.
Applications : Noted for its excellent CaCO3 scale inhibition and chlorine stability. Only Dequest® approved in boiler steam contacts with food. Cooling water treatment, boiler treatment, I & I Cleaners, swimming pool, stain prevention, metal ion control.
Storage : Material should be kept cool and dry for best results.
Shelf life : 3 years
Packaging : Drum; Tote; Bulk
Safety : UN 3265 CORROSIVE LIQUID, ACIDIC, ORGANIC, N.O.S., Class 8, PG III
Manufacturing site : Newport

---

Interesting. This was something that came with the pool, so it's probably old, I'll get rid of it, and get HEDP. We have a few bottles of this and that, that came with the pool. Everything that was from Leslie's Pool Supply did not have the actual chemical name on the bottle. Not one.
I had to look that info up on the web and found their MSDS sheet on a page not even connected with Leslie Pools. I think it's rather odd to package chemicals and not have the active ingredient anywhere on the label. Don't think I'll buy from them myself.

Thanks for the heads up on the sequential nature of the stain removal process. I will be careful. I set a vitamin C table on the worst stair stain, as I'd read it can be a good test to see if it's iron stain, and yep, the stain in that spot cleared up under the tablet. So, those stains probably are iron.

Interestingly, I have a koi pond also, and the best product for algae removal without hurting the fish or plants is the same ingredient as in the Polyquat, except at 4.5% strength. Works really well in fish ponds, as copper in any amount is toxic to fish, so good products can have lots of applications I guess.

Well, thanks for all the help. I'll post again when the test kit arrives.

Also, forgot to add, interesting that you only found that ingredient to take care of calcium scale, and not metals. Wonder why Leslie pools would name it Metal X in that case, hmm. Seems a bit misleading, to say the least. I can see now why most pool company products don't have a good rep here. lol.

You mentioned that you've been using trichlor pucks in the feeders, which do contain quite a bit of CYA and will raise it quickly. If you've been using the trichlor pucks for a long time, the algae growth is probably because the CYA has gotten too high and you're not maintaining adequate chlorine levels for it. I've skimmed through this thread a couple of times, and I don't see a CYA level listed...when you get your kit, please test for CYA and post that number.....

Before you do a stain removal process, check with me. I think I'm about to revise that process. In particular, you MUST have a full set of K2006 readings, especially including TA & CH.

Still waitning on the test kit. We closed the pool after my last post at 1.0 chlorine. Opened it today, 4 days later. The water is much clearer and a much lighter shade of green. The algae/whatever that was coating the walls is a lot less too, although back in a few spots. I tested today with the two-way test I have and Chlorine is back down to between 1.0 and 0.6, pH is steady at 7.8 (if the tests are accurate).

We added one more gallon of 10% chlorine, and brushed. Filter pressure was up again also, so we'll backwash too. I will be doing the second dose of polyquat this afternoon after the chlorine, brushing and backwashing. Then I'll test the chlorine again. We have one more bottle, if it drops this afternoon, I'll add the second bottle, if it doesn't, I'll test in the morning and add it then, if it needs it.(which it probably will).

I will do the CYA test as soon as the new test kit arrives (hurry, hurry mail!) I'm really
curious as to it's level too, since we've used nothing but the pucks for the last 3 years.
Before that the pool guy used them too, but I don't know if he supplimented with liquid chlorine or did any shock treatments.

But as I said, it looks so much better, I can see light at the end of the green tunnel now! lol.

Again, thanks for all the help!

My Husband went to get more liquid chlorine (he got 6 total) and while he was there picked up a 5-way kit because I just was not trusting the kit I had. Turns out my suspicions were right and we got rather differnent readings.
Looks like the chlorine reading was fairly accurate but the pH was not,

with the new 5-way kit (not the Taylor kit that's still in transit)
Free Chlorine-0.6
Combined Chlorine-0.6
pH-6.8
Total Alkylinity-120

We added one more gallon of 10% Chlorine and an hour later it was
1.0, both FC and CC.
the other two readings the same.

We added 1 more gallon chlorine (that's 3 gallons total today) and are closing the cover and will test again in the morning.
I have 1/3 a box of borax left, I guess I should get some more tomorrow.
So what now?
Thanks again.

Keep chlorinating and report the K2006 readings when you get them.

Water temperature is 85*F

We've been adding an average of 1 or 2 gallons of 10% liquid Chlorine almost everyday for the last week and have just kept it between 0.6 and 1.0 give or take. The cloudyness has cleared up and the green color has paled quite a bit but it's still rather green.

Also added 32 oz. of Polyquat in two doses, three days apart.

The yellow-green algae (I think it's algae, it puffs up like dust when we brush it, makes the water cloudy for about an hour before it's filtered out) that has been on the sides has lessened too, to about a few patches here and there the next day after adding chlorine and brushing. There is some spider web like staining on the sides in addition to the brown iron stains on the steps.

Where would I take the water to have it tested for metals, iron and copper?

Even though the green is less, it's still about the color of slightly diluted Mountain Dew or Gatorade. That's the best color match I can think of.

What next?

As best we can tell, metals testing used on pool water is NOT reliable.

One problem is that is that various pool products contain chemicals that can 'shield' soluble iron or copper from being measure. A second problem is that the tests only detect solubles, and simply the process of collecting a water sample, and carrying it to the store can change soluble metals to insolubles. When I used to collect water samples on a potable system, the sample used for metal testing had to be 'pre-charged' with acid and also had to be filled to eliminate ALL air space in the sample bottle.

The metals bucket test is intended to 'break' any 'shielding', drop ALL the metals present to the bottom, and give a reliable qualitative indications of metals present, rather than the quantitative, but unreliable results from various test kits.

Interesting, so for the lay person, metal testing is unreliable to the point of being useless? So do we just assume because my pool water had been on the acid side and I have mostly copper pipes, I probably have some copper?

To my knowledge, I haven't used any pool products that contain copper. I checked our chlorine pucks and they do not have copper.

I also looks like I left off the first part of my post with my test results. I tend to type in a document and then cut and past so I don't lose stuff if a posting goes wrong. So here it is again;

We recived the Taylor 2006A test kit today. Here's the results;

FC- 1.2 ppm
CC- 0.2

pH- 7.0

TA- 120 ppm
CH- 875 ppm

CYA- 90 ppm

Just use the 10mL sample instead of the 25mL one as it will save on your reagents.

Just added the last two gallons of 10% chlorine and 1/3 box of borax tonight after the sun was off the pool. FC was just about zero before the addition. We added 2 gallons last night too and only got it up to 1.2ppm. This a.m. it was pretty much gone.

The water is clear but still Gatorade green, although a little lighter shade. Still have the spider-web like staining on the sides. Could algae be collecting in fine cracks in the plaster? Could this be mustard algae? I've been reading about it, hope we don't have it. And of course, still have the brown iron stains on the stairs. Except for the two white spots where I placed two halves of a vitamin C tablet.

I'm getting pretty frustrated here. My husband seems to think 1-2 gallons of 10% chlorine a day should be enough and is skeptical that we need more. With a CYA level of 90ppm we should be running 5-10ppm chlorine levels at a minimum for manintenence and it looks like we need at least 20-75 for shock levels I think. I have no idea how many gallons that would be for either level. Do we just keep dumping in gallon after gallon until it regesters 20+ppm? And how many would that be? 5 gallons, 10, 20? I want to have the right amount on hand but what is that amount?
Is there a calulator somewhere or a formula that we could plug in our pool gallons + CYA level+ ppm needed? I'm not that good at math, but if I have a formula and a calculator I could probably figure it out. Or is it just add until it's enough, and hold it there for a few days? I guess I want to know how many gallons to have on hand. I don't want to keep running to the store every other day.
My drop dead date of September 1st is fast approching and I've lost a week just waiting for the test kit.

With our CYA levels at 90ppm we would need to keep our Chlorine levels at least to 5ppm for everyday maintenence let alone shock levels. Is there any other method to reduce CYA other than dilution of the pool water? If we dumped 20% of the water would that bring it down to 70%? That wouold be a more manageable level of chlorine to me.

Anyway I'm getting really frustrated and confused at this point. And I haven't even talked about the metal issues.

Your PF is 3.4. 10% chlorine -- if it's still full strength and if it's boxed bleach, it almost certainly is NOT -- contains 10% x 8.5lbs, or 0.85 lbs of chlorine. Multiply your PF x your available chlorine for 5.8 ppm of chlorine IN YOUR POOL, per gallon. In other words, 2 gallons of pool store bleach will add up to 6 ppm. 2 gallons of Walmart bleach (6%) will add about 3.5 ppm.

The fact that you added 2 gallons, and only reached 1.2 ppm tells me your pool store bleach is probably weaker than Walmart bleach!

Your husband is right -- 1 - 2 gallons should be more than enough per day, IF
+ your pool was algae free (but it's not!)
+ had no other chlorine demand (but it doesn't)
+ the pool bleach was full strength (but, in August, it's not)

=> Algae can collect in cracks. Both mustard and black algae do this. BOTH types are VERY chlorine resistant.

=> Adding chlorine, without adding ENOUGH chlorine to kill them, just leaves you in a Vietnam style conflict with your enemy, in which both sides take huge losses and neither side wins. You've got to make up your mind about whether you're willing to do what it takes to win.

=> There's no 'free' way to clean up your pool. We can help you do it better, and for less than a pool store would, but on a 35,000 gallon pool, you are going to have to spend several hundred dollars to get rid of your algae and clean up your stains.

=> You haven't 'lost' any time waiting for the kit: if we take off and start treating your pool without testing and proper prep you could spend several hundred dollars and accomplish nothing.

=> The "PoolCalculator" (poolcalculator.com) allows people to calcuate exact doses . . . but that's only helpful if you know the other stuff you need to know. For example, The PoolCalculator won't help you figure out that your 10% labeled bleach is currently probably 4%! You'd probably end up thinking the PoolCalculator has a math error.

=> This is extremely difficult water:

FC - 1.2 ppm
CC - 0.2
pH - 7.0
TA - 120 ppm
CH - 875 ppm
CYA - 90 ppm

I don't recall ever seeing a calcium level that high, before.

=> Under the circumstances, what I'd recommend is
+ Realize you can NOT use cal hypo (calcium will turn your pool to milk), or
+ Trichlor or dichlor (will add MORE stabilizer)
+ Which leaves bleach . . . BUT your pool store bleach has 'cooked off' in summer heat;
+ Which leaves you buying dozens of gallons of Walmart bleach!
+ 10 gallons tonight; and 10 gallons tomorrow night + brushing would be a start.
+ You MUST keep your pH low, so you need to read the muriatic acid page (see my signature), and get a couple of gallons at Lowes.
+ Once the algae is under control, you have to lower your calcium, because HEDP won't work properly with that much calcium in your water. That's a major process, too.
+ You need to order polyquat, because that's the only thing you can leave in your water while you are messing with all the other stuff.
+ Once you have controlled the algae (not: eradicated -- that's probably not practical, right now!) and lowered the calcium, THEN you can tackle the stains.
+ The only easier path I can think of, is drain and refill, BUT you need to (a) check on the cost, and (b) make sure it will help by testing your fill water and making sure IT doesn't have super high calcium, AND (c) check to make sure there aren't local restrictions on draining and refilling (you are in California, where such restrictions are common).
+ To make SURE you are testing calcium correctly, please watch the Taylor calcium videos on this page: http://www.poolforum.com/pf2/showthread.php?17157

So . . . it's up to you. What do you choose to do?

Quote:

---

Originally Posted by PoolDoc

Your PF is 3.4. 10% chlorine -- if it's still full strength and if it's boxed bleach, it almost certainly is NOT -- contains 10% x 8.5lbs, or 0.85 lbs of chlorine. Multiply your PF x your available chlorine for 5.8 ppm of chlorine IN YOUR POOL, per gallon. In other words, 2 gallons of pool store bleach will add up to 6 ppm. 2 gallons of Walmart bleach (6%) will add about 3.5 ppm.

The fact that you added 2 gallons, and only reached 1.2 ppm tells me your pool store bleach is probably weaker than Walmart bleach!

Your husband is right -- 1 - 2 gallons should be more than enough per day, IF
+ your pool was algae free (but it's not!)
+ had no other chlorine demand (but it doesn't)
+ the pool bleach was full strength (but, in August, it's not)

=> Algae can collect in cracks. Both mustard and black algae do this. BOTH types are VERY chlorine resistant.

=> Adding chlorine, without adding ENOUGH chlorine to kill them, just leaves you in a Vietnam style conflict with your enemy, in which both sides take huge losses and neither side wins. You've got to make up your mind about whether you're willing to do what it takes to win.

=> There's no 'free' way to clean up your pool. We can help you do it better, and for less than a pool store would, but on a 35,000 gallon pool, you are going to have to spend several hundred dollars to get rid of your algae and clean up your stains. I don't mind spending the money if we get a clean pool, money to me is not the biggest obstetrical. But my husband is still not getting this. (sigh)

=> You haven't 'lost' any time waiting for the kit: if we take off and start treating your pool without testing and proper prep you could spend several hundred dollars and accomplish nothing. True

=> The "PoolCalculator" (poolcalculator.com) allows people to calcuate exact doses . . . but that's only helpful if you know the other stuff you need to know. For example, The PoolCalculator won't help you figure out that your 10% labeled bleach is currently probably 4%! You'd probably end up thinking the PoolCalculator has a math error.

=> This is extremely difficult water:

FC - 1.2 ppm
CC - 0.2
pH - 7.0
TA - 120 ppm
CH - 875 ppm
CYA - 90 ppm

I don't recall ever seeing a calcium level that high, before.

=> Under the circumstances, what I'd recommend is
+ Realize you can NOT use cal hypo (calcium will turn your pool to milk), or
+ Trichlor or dichlor (will add MORE stabilizer)
+ Which leaves bleach . . . BUT your pool store bleach has 'cooked off' in summer heat;
+ Which leaves you buying dozens of gallons of Walmart bleach!
+ 10 gallons tonight; and 10 gallons tomorrow night + brushing would be a start. He's at Walmart now getting 10 gallons of chlorine. But he keeps insisting on getting the 10% pool chlorine, saying it's cheaper. He agreed that the chlorine he bought before was probably dissipated as he buys it at Home Depot and they keep it in the shade but it is outside. I have to work tomorrow, so Monday I'm going to Walmart and get 10 gallons of plain bleach from the laundry area.
+ You MUST keep your pH low, so you need to read the muriatic acid page (see my signature), and get a couple of gallons at Lowes. pH was 7.0 yesterday, will check again today. We still have about 1/2 gallon of muriatic acid on hand, I can get more.
+ Once the algae is under control, you have to lower your calcium, because HEDP won't work properly with that much calcium in your water. That's a major process, too. Then I guess it not a bad thing that I don't have the HEDP yet.
+ You need to order polyquat, because that's the only thing you can leave in your water while you are messing with all the other stuff. I did add 32oz. of polyquat, so I guess this means I need more.
+ Once you have controlled the algae (not: eradicated -- that's probably not practical, right now!) and lowered the calcium, THEN you can tackle the stains. At this point I am putting stain removal on the back burner.
+ The only easier path I can think of, is drain and refill, BUT you need to (a) check on the cost, and (b) make sure it will help by testing your fill water and making sure IT doesn't have super high calcium, AND (c) check to make sure there aren't local restrictions on draining and refilling (you are in California, where such restrictions are common). Don't think our county has those restrictions, but I'll check.
+ To make SURE you are testing calcium correctly, please watch the Taylor calcium videos on this page: http://www.poolforum.com/pf2/showthread.php?17157

OK I did that test now 3 times, 2 times with the instructions to counteract possible high metal ions interference.
I got regular test; 875ppm
interference test; 750ppm both times.


So . . . it's up to you. What do you choose to do?

---

Just to check I tested the source water;

FC- 0.5
CC- 0.5
pH- 8.0
TA- 75
CH- 75

So our water is a little hard but not much and it looks like the test is good. Could limestone have been leaching into the pool water for a long time? Could this cause such high calcium? We do need to re-plaster soon, we figured we'd do it next summer. If that's the problem with the calcium levels, maybe we'll just try to get rid of the algae and forget the stains, etc. and re-plaster this fall. sigh

Thanks for all the advice, sorry if I sounded impatient, etc. I know everyone is just trying to help and I do appreciate it. I am trying really hard to convince my husband to give up on the pool chlorine and just get plain bleach. He doesn't see the difference even though he admits the Home Depot chlorine is probably weak this time of the summer. We don't use the pool store.
He's figuring that the Walmart pool chlorine has been inside the air conditioned store so it's gonna be better. But I also noticed that the plastic bottles the pool chlorine is packaged in is much thinner than bleach bottles, so it could leach just from that I think even inside a cool store. So I'll get the plain bleach Monday. Thanks again.

Given your source water, I'd DEFINITELY recommend looking at the cost of a partial drain and refill. You actually don't want to drain ALL the way, since with a concrete pool you actually DO have to do all that "water balancing" stuff we normally tell people to ignore -- you NEED more calcium in the water than your fill water has.

Or not -- it would be easier to remover the stains with the soft water, then adjust the 'balance' later, after the metal is gone.

By the way, lime stone (calcium carbonate from the marble dust in plaster, probably) does NOT dissolve into pool water UNLESS your pH is low, as in below 7.0. Given your fill water I'd guess you either had (a) a period where the pH was way too low, OR (b) used calcium hypochlorite shock or chlorine powder for an extended period.

Just thinking. If budget is not a big problem AND you are not planning to re-plaster next spring (which would fix the stains), THEN you might want to do this:
1. Drain the pool.
2. Do a BLEACH rinse to remove as much algae as possible.
3. Refill with soft water.
4. Superchlorinate -- no stabilizer.
5. Then, transition to stain clean-up.
6. Then set up your pool for normal use, and a good winter shutdown, so you are ready to go next spring.