My pS234 test results

[lskeate]

Opened the pool this week and found crystal clear water. What a pleasant surprise. I took a sample to the pool store yesterday and then ran my own PS234 tests this morning. Here's the drill.

Pool store My pS234 kit
FC 14.4 9.5
CC 1.1 00
pH 8.2 8.2
ALK 288+ 280+
CYA 140 150+
CAL 600+
Hardness 340
TDS 3900
Copper 0.07 (is this important?)

It is a fiberglass 20,000 gallon pool. Our local water supposedly runs 1500ppm TDS. Pool store tells me I need to drain some water, but I couldn't make contact with the local Viking pool people yesterday and of course they don't work on Saturday. I bought lots of muriatic acid last year from the black hole of a pool store. Spent all season with incredibly high chlorine or fighting algae. Any ideas? I'm willing to drain but I want to talk to the Viking people first so I'll know how much I can safely drain.

I admire all you chemists who understand this stuff. I've been reading for two summers now and it just gets more confusing!! One more question. Is there a drop test for Ph so you don't have to rely on comparison? Thanks for your help.

[aylad]

Congratulations on the clear water, it's a beautiful thing, isn't it? :)


What do you use for chlorination in your pool? I'm guessing it's trichlor tabs since your CYA is so high--and do you know where the copper came from? Did you use a copper-based algaecide when you closed?

Your calcium level is high--do you have a lot of calcium in your water? Do you notice any scaling in the pool?

I would not be concerned about the TDS--it's usually something that you only have to worry about if you're having continual algae blooms that you can't kill that don't have any explanation. However, your algae problems are almost certainly caused by your CYA level, which is WAY WAY high. So....you don't need to necessarily drain water to reduce the TDS, but you do need to drain and refill water to lower your CYA. You really need to shoot for 60 ppm or less, and then you don't have to run the chlorine so high and won't be fighting algae all summer. In addition, unless your fill water is high in Calcium, you will also be able to lower your calcium a bit.

Use the muriatic acid to lower your pH and alk--lower the pH until it's around 7.0 (this will also lower your alk) , then aerate your pool to raise the pH back up without also raising the alkalinity.

As far as the copper goes, higher levels of copper in the water would make a difference because high levels of chlorine can make the copper fall out of solution in the water and cause green staining (that's where you get green hair and nails that many people blame on chlorine), but the level that you describe shouldn't cause you any problems. I would not use anything else that contains copper in your pool, though, because once it's in there it doesn't come out.

There is not a drop test for pH that I know of--there has been some mention around the forum of an electronic pH test, but I've gotten the impression that they are not reliable unless very meticulously maintained.

Janet

[CarlD]

With FC that high you cannot be sure your pH isn't artificially raised. Try a couple of drops of chlorine neutralizer in it first (Taylor-0007--or the first two drops you put in when running the Total Alkalinity test--before adding the dye.

I personally don't like CYA that high--draining half your water and refilling will get it down to 70-75--high but much easier to manage. At 150, you need a constant FC of 8-15ppm.

[mbar]

Did you test your fill water? With such high alkalinity and calcium, it would be better to drain 1/3 of the water out, refill, drain 1/3 and refill and do it again until the alkalinity, calcium and cya are in normal ranges. If your alk and calcium are high in your fill water, then the only thing that will lower will be the cya - which is a good thing, because with such high cya, you would need very high chlorine numbers continuously as Carl says. I have a fiberglass pool and I have never had a problem draining and refilling this way. If you don't have a high water table, you can take it down a half at a time. With the high chlorine levels you will get false ph readings, therefore it really is in your best interest to take the cya down so that you can run your chlorine at lower levels without getting algae. When the water is balanced properly, it is much easier to keep a sanitized pool. We are here to answer any questions you may have:)

[waterbear]

Opened the pool this week and found crystal clear water. What a pleasant surprise. I took a sample to the pool store yesterday and then ran my own PS234 tests this morning. Here's the drill.

Pool store My pS234 kit
FC 14.4 9.5
How old is your FAS-DPD titrant? This reagent DOES have a shelf life and should be replaced yearly. Taylor R-0781 is the reagent you want. FYI, the DPD powder is Taylor R-0780.

CC 1.1 00
pH 8.2 8.2

ALK 288+ 280+
This is well within the accuracy range of the drop test so they are the same.

CYA 140 150+
Once again well within the accuracy range of the drop test, which only is really accurate up to 100 ppm. If your pool store used a colorineter (a meter that read the test result vials) then they are probably right on the money.

CAL 600+
Hardness 340
TDS 3900
Copper 0.07 (is this important?)
This small amount of copper can be ignored. It might have come from your fill water or runoff from rains. It is essentially 0ppm. Don't worry about it unless it tests at about .2 ppm or higher.

It is a fiberglass 20,000 gallon pool. Our local water supposedly runs 1500ppm TDS. Pool store tells me I need to drain some water, but I couldn't make contact with the local Viking pool people yesterday and of course they don't work on Saturday. I bought lots of muriatic acid last year from the black hole of a pool store. Spent all season with incredibly high chlorine or fighting algae. Any ideas? I'm willing to drain but I want to talk to the Viking people first so I'll know how much I can safely drain.
Don't worry about TDS. It's a bogus measurement in most cases.

I admire all you chemists who understand this stuff. I've been reading for two summers now and it just gets more confusing!! One more question. Is there a drop test for Ph so you don't have to rely on comparison? Thanks for your help.
Hope you find this helpful.

Edit: there really isn't a drop test for pH and meters are not a good idea for several reasons. Some people find that the Taylor pH test found in the 2000 series test kits that use a different reagent (R-0004) and a larger comparator tube (45 ml) a bit easier to read but I personally dont see a difference between it and the small comparator and R-0014 reagent used in the PS-234. The least epensive way to get this comparator is with the Taylor K-2000 starter kit which has the pH test with acid and base demand and the DPD chlorine test. You already have all the other tests you need so buying one of the more expensive K-2000 series testkits like the K-2006 or K-2005 will only dupicate the other tests.

[lskeate]

I appreciate the responses. This is where I stand as of today, Monday. I ignored the pool yesterday. This morning I retested. My FC is now 4 with 0 CC. PH, I think, is still at 8.2. CYA is sill somewhere near 150. I called our city and the calcium level in our city water averages 100ppm. I don't seem to have a scale problem along the water line. I do get a lot of scale on the top of the bubble solar cover, but it easily washes off. I'm guessing I should not rinse that back into the pool when I clean my cover.

I called the local Viking Pool company here in Midland, TX and spoke to the "expert". He wasn't aware of CYA or stabilized chlorine. He did tell me I should follow the directions with the drops in the test kit. Thanks for the advice. I asked him if there is a national help-line phone number for Viking Pools, he said no, I thanked him for his help and hung up quickly. He also told me before I drain the pool I should put 2x4s along the width of the pool, then drain it 2 feet. The pool depth is 8 feet. I'm afraid I'd be draining and filling all summer. We have a very low water table in Midland. You can dig a cemetery plot and not find any water.

I guess I need to start doing a 1/3 drain and refill, then retest. Since I'm going to this trouble, what is the perfect CYA reading? I've ordered some new reagents so I'll know exactly where I stand. One last question about chlorine. I used bleach exclusively last summer and that's what is in the pool now. Or used to be. How can my free chlorine go down so far in about 40 hours when the stabilizer is so high and there is no combined chlorine? The pool is covered with a bubble cover and is pretty cold, but I can't give you an exact reading. I know I should have paid more attention to my chem professor. But it was so boring!! Thanks again to all of you. Wish we would have been introduced the first summer we planted this pool.

[aylad]

You definitely need to do a series of drain/refills to lower your CYA, and I would shoot for about 40 ppm. I don't know where you live and how much sun your pool gets, but it's way easier to add more CYA later if you need it than to reduce it, as you are finding out. At least the good news is that your calcium and TA will drop, as well.

Seeing a chlorine level drop from 9.5 to 4 in a couple of days' time is not that surprising, especially if you have sun on the pool over a long period of time. Your pool will be so much easier to deal with once you finish the refilling! :)

Janet

[lskeate]

We did a series of drains on our fiberglass pool. On Friday afternoon, took a sample to the private pool store and they said I was at 15ppm CYA. Said the alk was 226 and pH was 7.8. Then I took a sample to L****es. They said I had 40 CYA and 7.8 pH. She also said I had high phosphates, but I recall you guys think that's a Leslies thing. Then on Saturday morning I took another sample back to the private pool store (who runs tests with a computer) and they said my CYA was 35ppm with Alk of 200 and pH of 7.7. My own CYA test, which I have challenges with, shows closer to 40.

So, where should I go from here? They tell me I should add a gallon of Muriatic acid, which I'm willing to do. I'm tempted to add the acid and then just follow the chlorine closely. Anybody have a better idea?

[Watermom]

Add doses of muriatic acid and get your ph down to about 7.0. Instead of a big dose of acid, small doses and just keep checking ph. This will also drop your alk. Then, aerate your ph back up. when it gets back up to about 7.6 or so, recheck your alk. If it is still high, repeat the process.

More info can be found at the following link:
http://www.poolforum.com/pf2/showthread.php?t=191

CYA of 35 or 40 either one is perfect in my opinion. Stick with bleach for your sanitation instead of trichlor pucks or you'll be right back up there with high cya before you know it. Keep us posted how things are going. Sounds like you are almost there!

[dstagg]

Why would anyone recommend draining several times instead of one large time. It would require draining much more water in the long run by draining several and get same results with one large drain.

[lskeate]

I have a fiberglass pool.

[Watermom]

You can't drain a pool down too far or you may have it pop out of the ground if you have a high water table. Thus, the need to do several smaller drains instead of one big one.

[CarlD]

Since your T/A is 200ppm in a F/G pool, I think you are close to done on that--anything under 180ppm you should be OK.

A CYA of 40 or 50 is great--you'll use less chlorine but it won't break down in sunlight.

TDS is nonsense 99% of the time (every SWG owner has TDS that's "too high").

And, of course, phosphates is the latest scare tactic. Only worry about phosphates when our cleanup methods don't work.

I think you are doing great!

[lskeate]

Pool still looks great. It's not chewing through the chlorine. But I still have a couple of questions. When "Watermom" tells me to slowly add muriatic acid, what is slowly? A quart, half gallon, gallon? The pool store printout wants me to add 3 gallons!

"Carl" says I'm almost there. If I get my ALK down to 150-180, am I still aiming for a Ph of 7.5-7.7?

Also, some people mention the pool's exposure to the sun. I live in west Texas where the sun is always shining and my pool is in the sun for the majority of daylight hours. What if I keep a bubble cover on the pool when we aren't using it? Does that help stabilize your chlorine? Once I figure out the exact amount of bleach to maintain the desired chlorine level, is it going to require more as the water gets warmer?

As always, I appreciate you moderators and your vast knowledge of pools and chemistry. I was an accounting major which helps balance the checkbook but not chemicals.

[waterbear]

Why would anyone recommend draining several times instead of one large time. It would require draining much more water in the long run by draining several and get same results with one large drain.
Fiberglass pools need special precautions if they are going to be drained more than about a foot below the skimmer. They might need to be braced with boards to prevent buckling or they might need to have ground water constanly pumped out from under them (the latter could apply to gunite and shotcrete pools also!)

[waterbear]

Since your T/A is 200ppm in a F/G pool, I think you are close to done on that--anything under 180ppm you should be OK.


Sorry to disagree with you on this one Carl but if the pool is being chlorinated iwth bleach there will be much better pH stability and less acid demand if the TA is more like 70-90 ppm. I have seen this time and again with my customers using liquid chorine or with SWGs and now recommend it as a matter of course. I also apply this to my own fiberglass pool.

On the other hand, if the pool is being chlorinated with (gasp!) trichlor or dichlor, then a TA up to 180 ppm is probably OK but under 150 would be better. (I preper to keep it between 100-120 ppm).

(I know you weren't sleeping through all the discussions Chemgeek and I had about outgassing of CO2!;))

[CarlD]

Since Evan sees firsthand F/G pools, I'd tend to take his advice first. In vinyl pools, I've seen t/a of 180 with no problems.

As for muriatic acid, "slow" usually means a cup to a quart pour VERY slowly into the return stream. Better still is to pour it SLOWLY into a 5 gallon bucket of water, then pour THAT into the return stream--less chance of stray acid reaching the pool wall.

3 gallons????!!!??? Maybe if your pH was 9.5 in a 48,000 gallon pool and you wanted to make it into an acid wash! Pool stores! Feh!


We believe in slow and gradual for all chemicals other than chlorine. If your pH is still in the 8's I'd add about 1/2 quart of muriatic acid and wait 12 hours, then check pH again. That's because you have 20K gallons and your pH is very high. Otherwise, I'd suggest half that--1 cup.

[waterbear]

Since Evan sees firsthand F/G pools, I'd tend to take his advice first. In vinyl pools, I've seen t/a of 180 with no problems.
It applies to vinyl also. However, many AGPs don't have as much aeration from the returns and don't have water features compared to IG so there is less aeraton so they can get away with higher TA without major pH problems. However, lowering the TA will still contribute to pH stability. It's the basic chemistry involved!
As for muriatic acid, "slow" usually means a cup to a quart pour VERY slowly into the return stream. Better still is to pour it SLOWLY into a 5 gallon bucket of water, then pour THAT into the return stream--less chance of stray acid reaching the pool wall.

3 gallons????!!!??? Maybe if your pH was 9.5 in a 48,000 gallon pool and you wanted to make it into an acid wash! Pool stores! Feh!
This amount is what would be needed to lower the TA ,not for pH adjustment, BUT I wold not put it all in at once. I would follow the sticky on how to lower TA. This is around the total amount of acid that would be needed to do it.
Adding acid lowers TA, aeration brings the pH back up without causing the TA to go up again.

We believe in slow and gradual for all chemicals other than chlorine. If your pH is still in the 8's I'd add about 1/2 quart of muriatic acid and wait 12 hours, then check pH again. That's because you have 20K gallons and your pH is very high. Otherwise, I'd suggest half that--1 cup.

Until the TA is lowered the pH is going to be moving toward 8.0 fast and the acid consumption will be high.

[PhantomAndy]

You can't drain a pool down too far or you may have it pop out of the ground if you have a high water table. Thus, the need to do several smaller drains instead of one big one.

You can float the liner in vinyl pools as well. The rule of thumb with virtually all pool types is no more than 1 foot below the skimmer.

My water table is so high I never go more than a hair below the return lines (about 4 inches below skimmer level). We have a high water table here and even that's risky enough.