My pS234 test results

[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]

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.

[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.