Where'd the CYA go?

[usmarinemike]

I've moved to a house with a marginally well taken care of pool, and it's my first pool so I've been getting it and myself up to speed over the past few weeks. I think it must have been covered up right after hurricane Irene last year. I left it covered and opened it up several weeks ago to see it coated in green and all kinds of interesting crud lying on the bottom. It's all vacuumed out (finally) and I brush it every day. I have a few problems (it's green) but this post is only going to focus on one of them. I have also come to despise pool stores (Don't tell me there's no way I can truly understand all of these chemicals and tests (simply because you don't)). Anyway, that's another story. So I take my water a few weeks ago and my CYA is 20ppm. Low. Fine. I forgo buying the 3# for $25 of pool store stabilizer and go get the Aquachem for $12. Afterall, it's labeled 100% CYA so how messed up can it be? Add about 2.5# using a boot sock tied to the inside of my skimmer pot. I took more water in to the pool store about a week later and they still say the CYA is 20ppm.

What gives? Poor testing? Something metabolizing my CYA? Poor product? It was tested by the same person on the same machine.

17,500g 27' AG round Hayward Powerflow LX with Hayward Dreamline sand filter and I'm just about to pull the trigger on a legitimate test kit.

[Watermom]

If the original 20 was right, then you should have about 40ppm of CYA in there now. Don't add any more at this point until you do what you know you need to do -----pull the trigger and get the good kit! (You can get the Taylor K-2006 or2006C through the testkit link in my signature below.) Then, you will no longer have to rely on anybody other than yourself to test your water and you will know what your readings actually are.

Welcome to the Pool Forum!

[usmarinemike]

Another question (don't have other posting privileges yet). I'm working on getting rid of the green. Regardless of CYA level, should I keep dumping the Cl in throughout the day to keep it at shock level or just morning and night?

[aylad]

The chlorine that you put in in the evening is working more efficiently than what's put in during the day, because the sun is helping consume the daytime additions....but that being said, the more consistent you are about keeping it at shock level, the quicker the algae will die. If you are home and able, then by all means add Cl during the day, too....but if you're not home, then morning and evening will also work, it may just take a little longer.

[PoolDoc]

Don't add CYA, till the pool is no longer green -- algal biofims can incorporate bacteria that metabolize CYA to ammonia or worse. Since you have some CYA, go ahead and add plain 6% household bleach at the rate of 3 gallons per dose till you read the "orange" level on an OTO (yellow drops) kit. Hold your chlorine level there until you get a K2006, and can accurately test both chlorine and CYA levels.

Check your pH BEFORE the chlorine gets that high and adjust it to between 7.0 and 8.0. Use 20 Mule Team borax to raise; muriatic acid (see page link in my signature) to lower.

Put your sand filter on recirculate -- it won't filter that stuff and we're beginning to think those undersized over-driven AG sand filters actually fragment algal particles into an even finer and harder-to-filter slurry.

Read the test kit, muriatic acid, and Best Guess pages in my signature -- they all apply.

Just curious -- nothing to do with pools -- are you at Lejeune?

[usmarinemike]

OK. That's pretty much what I've begun doing. If the FC gets below the top level of the OTO test I use poolcalculator to figure out how much to take it back up to shock with the BGC. I have a giant bucket of 73% cal-hypo that I've been using to keep the level up that I bought before I became disgusted with the pool store. It was a long time coming, and she looked me straight in the face and told me that sodium bicarbonate and sodium hydrogen carbonate were not the same thing. She also told me that I couldn't test things myself. I had to use her machine. Our relationship was over even before I found your site.

I agree on the sand filter. I knew I was in trouble when I saw that the pump was rated at 70gpm, and the max rating for my filter was around 55. It says it right on the side in big numbers. Who comes up with this crap? Could this be the reason that although my water is green, it's not swampy and I can see all the way through it? My algae is just really fine?

[PoolDoc]

Who comes up with this crap?

The same sort of people that sell Lipitor instead of generic statins that work better for 1/4 the cost. I'm guessing you can think of a few similar examples that made it through the US Navy or Marine Corps supply chain. Deception, deliberate product ignorance, and outright lying are fundamental qualities of marketing in US society. The only thing unique about what's happening in the pool industry, is that I know enough about pools and pool chemicals to recognize most of it. With medical products or consumer goods, I can only recognize a little bit of it.


Could this be the reason that although my water is green, it's not swampy and I can see all the way through it? My algae is just really fine?

If it was green WITHOUT algae, it would probably be iron at low pH. But, green with algae on the sides, is probably still algae. If you've got a white five gallon bucket, you can test and see:

1. Fill a CLEAN white 5 gallon bucket to pool water, to within 6" of the top.
2. Add 1/2 cup of baking soda, and mix.
3. Add 2 cups of 6% bleach, and mix.
4. Cover and wait 24 hours
5. If you have brown or khaki sediment, it was algae. Red-brown or orange sediment, it was iron. Something else - tell us about it.

[usmarinemike]

Just curious -- nothing to do with pools -- are you at Lejeune?

Actually at MCAS Cherry Point.


The only thing unique about what's happening in the pool industry, is that I know enough about pools and pool chemicals to recognize most of it. With medical products or consumer goods, I can only recognize a little bit of it.

I will never pretend to know as much as I perceive that you know about pools and pool chemicals, but a blue collar upbringing and a degree in Physics made me instantly distrustful of what the pool stores have been trying to lay down on me.



If it was green WITHOUT algae, it would probably be iron at low pH. But, green with algae on the sides, is probably still algae. If you've got a white five gallon bucket, you can test and see:

1. Fill a CLEAN white 5 gallon bucket to pool water, to within 6" of the top.
2. Add 1/2 cup of baking soda, and mix.
3. Add 2 cups of 6% bleach, and mix.
4. Cover and wait 24 hours
5. If you have brown or khaki sediment, it was algae. Red-brown or orange sediment, it was iron. Something else - tell us about it.

My pH right now is about 7.4. I've actually thought about maybe having an alkalinity combination that is somehow causing iron to precipitate out of solution. But, eh, I'm not adding baking soda until I can test TA myself. I also caved and added something called metalfree about 12 days ago. It didn't do much that I could tell so I decided to keep working on the sanitizer levels and come back to the metal idea later if I need to. I have my water up superchlorinated right now so I'm going to do the bucket thing and just add baking soda and see what happens.

[PoolDoc]

I also caved and added something called metalfree about 12 days ago.

Arg-gh! We need to know EXACT brand and product name of what you added. Depending on what it was, the bucket test may not work now.

[usmarinemike]

Arg-gh! We need to know EXACT brand and product name of what you added. Depending on what it was, the bucket test may not work now.

Natural Chemistry Metal Free. The whole liter. Pool additives without the contents on the bottle make me want to Hulk smash something. Can you enlighten me on these metal fixers/removers/deactivators? I didn't find a big discussion on them in Pool Solutions and I haven't dived into the deeper reaches of the forum yet.

[PoolDoc]

OK, I was hoping it was that product -- the current version (it changed mystery ingredients a couple of years ago, from EDTA to citric acid, with no notice) is not a problem, because once you had a chlorine level in the pool for 24 hours, it was gone. So, it should no longer be present, and should not have (or will not) interfere with the bucket test.

[usmarinemike]

Bucket test not complete yet.
Filter set to recirculate.
Pool is noticeably less green today. I even want to take my 2 year old swimming.
Lots of white junk in drifts on the bottom. Had this before but always thought it was leftover cal-hypo that didn't dissolve. There's more than ever today even though I was very careful about distributing the cal-hypo last night. I have been brushing it off the bottom, but I'm beginning to think this stuff is my culprit. Does that dog hunt? How is the Cl pushing the Fe out of solution?

If this is metal I want to vacuum it out. Heck, I'll vacuum it out even if it's not. Problem is, I could lose my progress if I vacuum to filter and it blows through, and I might lose my progress (or maybe make it worse) by vacuuming to waste and needing to refill with the water hose. So short of doing a rain dance I don't know what to do.

[PoolDoc]

White stuff is not iron or copper . . . unless you've added aluminum sulfate, it's probably calcium carbonate from your cal hypo.

You should vacuum it up, and then backwash your filter. If it blows through, vacuum to waste, and THEN check for filter for sand loss. Do you have a 2 speed pump? If so, run on low.

[usmarinemike]

White stuff is not iron or copper . . . unless you've added aluminum sulfate, it's probably calcium carbonate (edited - Pooldoc) from your cal hypo.

Aluminum Sulfate is typically used as flocculant, right? Didn't put any in, unless someone has discharged a fire extinguisher into my pool lately.

[usmarinemike]

Bucket test just stayed cloudy white. The pool finally went from green to blue last night. Here are my numbers this morning after testing with the K2006.

pH 7.3
TA 70ppm
CYA is just below 30. The dot disappeared with room for maybe a half a drop in the comparator before it overflowed.
FC=1.2 CC=1.2

Thing about the FC is that I put in almost 3 lbs of 73% cal-hypo last night. It certainly did it's job that time, but woah. I guess I'll be working down the chlorine demand every night for a while longer. At least it's finally blue and inviting.

What are the reasons/advantages/disadvantages to putting the cal-hypo directly into the skimmer?

[PoolDoc]

The disadvantage is that it's dangerous, if you don't make 100% certain that there are no OTHER chemicals it can encounter before reaching the filter.

The advantage is that you put the excess calcium on the filter, instead of the pool, and in the process, get improved filtration. If you do NOT do it this way, you'll tend to have problems with calcium build up, with scale and cloudiness resulting.

[usmarinemike]

Alright. Two nights in a row I've added enough chlorine to bring the pool up to the shock region on the BGC, and both nights the pool tested much, much lower 2 hours later. Tonight I started with .8ppm FC and added 3.5 gallons of 6%. I now have 2.0ppm. Lat night I added about 3lbs of 73% cal-hypo and 2 hours later it was around 2.0ppm. So two different Cl mediums show some wicked chlorine demand? To recap, the thread started with my missing 2.5 lbs of CYA. Does this sound close to the chlorine demand from ammonia? My pool went from clear green to clear blue last night, but I have a feeling that my adding a lot of the cal-hypo to the skimmer last night allowed my sand filter to finally hang on to whatever was in the water. What's going on?

[PoolDoc]

Two nights in a row I've added enough chlorine to bring the pool up to the shock region on the BGC, and both nights the pool tested much, much lower 2 hours later.

That's pretty definitive evidence that your pool had some CYA that got bio-degraded to ammonia or urea. But unless you want to take your water to a EPA certified lab, and have them do tests for COD (Chemical Oxygen Demand) and ammonia, we don't really have any idea how much ammonia is there, and consequently, we don't know how much chlorine it will take to clean up. We've seen it take 100+ gallons of household bleach on several occasions, when the CYA was very high the preceding fall.

But, knowing doesn't change anything: you're limited in how much chlorine you can prudently add at one time, both for the sake of your liner, and also to avoid the situation where you add a 50 ppm dose of FC when you only have 5 ppm of chlorine demand left!

By the way, keeping the pH on the high side of things, helps push the process toward less noxious intermediate products, as the chlorine breaks down the ammonia (or whatever is there in your pool).

[usmarinemike]

Working the pH up a little at a time. The owner used trichlor last season, and I assume every season because the floater was pretty beat up so the CYA was probably pretty high. I suppose 100 gallons isnt so bad. Great Value is about $1.50 this week. This will be one clean pool once the Cl holds.