New Pool Tests

[paigeag]

We had a new 21' AB pool set up a week ago, still waiting for electric to be run. 12 inches of water sat in it until we filled it yesterday. We added 1 gallon of the liquid stabilizer (instant conditioner) and 28 oz chlorine to try and target 2 ppm. Ran pump all night on extension cord and ran tests this morning. Results as follows:

Ph: 7.8
FC: 3
CC: .5
TA: 300
CYA: at 30 I could still slightly see the black dot, so I'm thinking it is between 20 and 30

Any help would be much appreciated, we are new to this. Thanks!

 

[Richard320]

Looks like you're doing pretty good for the first try.

Your pH is at the upper limit and the TA is high, so it will likely go over 7.8 today. So you need some acid.

Poolmath figures your pool at 10,400 gallons if the water is 4' deep. And if that's true, then the gallon of liquid stabilizer should have gotten you to 36. Did you rinse the jug to get every last drop of that liquid gold? If the water's deeper, or you have a deep end, then the volume will be greater and the CYA of course will be lower. It's still a day or two too early to sweat the CYA. Give it time to mix.

Now that you're doing, a lot of what you've been reading will make more sense. It might be a good time to study Pool School - PoolMath so you can utilize all the features of poolmath effectively. It can calculate volume, set target goals (hint: just use the Now TA as the target for now) and calculate how much of what you need to get things into range.

 

[paigeag]

I should also add that the water was clear but we think some spots of algae were starting to grow on the bottom (some darker spots).

 

[Richard320]

I should also add that the water was clear but we think some spots of algae were starting to grow on the bottom (some darker spots).

Brush 'em. Brush the whole pool, in fact. And don;t forget that chlorine is a consumable item. You'll need to feed some more of that to the pool today, too.

 

[tim5055]

I should also add that the water was clear but we think some spots of algae were starting to grow on the bottom (some darker spots).

Keep the chlorine high, even up to shock level and give it a good brushing today. With the chlorine at or near shock level perform an OCLT tonight to confirm if anything is growing. Overnight Chlorine Loss Test

 

[paigeag]

Thank you!!

 

[paigeag]

I have a couple more questions, please

My husband took the water to the pool store after we tested just to compare the results, they got:

FC .6 (why would this be so far off from what we have?)
TC .6
CC 0
PH 7.9
hardness 290 ppm
alkalinity 336
CYA 15

I used my reading of 300 for TA and 7.8 PH in the calc and it said to add 28 oz of muriatic acid. The pool store is recommending adding 3 gal of champion muriatic acid split between three treatments allowing 6-8 hours between each. Why is the amount so different? I made sure I had the correct % checked in the calc.

 

[Richard320]

Rule number 1: Pool store tests are unreliable.

Part 2: FC breaks down fast in sunlight. A small bottle has no depth so UV penetrates the whole way and can deplete it all in an hour.

Part 3: the pool store is advocating the "slug" method to lower TA. All that will do is render the pool unswimmable for a few days because the pH will be too low and possibly damage the liner where the dense cloud of acid settles. You can read why it's nonsense here: Acid column myth

Rule 2: Trust your own test results!

It's been proven over and over and over here that your results and the pool store's will never agree.

Anyway, you and your husband will have to decide who's in charge of the chemistry (Too many cooks and all that) and whose advice you're going to take. TFP and pool store methods don't mix. There are no shortcuts; believe in the process and trust the experts - thank you TFP

 

[paigeag]

Thank you! Ok, I will follow the pool calc recommendations and go from there.

 

[tim5055]

If you have read around here much you have probably seen that not much credence is given to pool store testing. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing. In my case two different pool stores told me my CYA was "fine", around 70 or 80. When I tested myself I found it over 200.

 

[paigeag]

I think everything is going pretty good so far, water is clear and I'm getting the hang of testing and using the calc. Chlorine has been holding really well. Last night we added acid to drop ph to 7.2 to try and get the TA down and have the return pointed up for aeration to bring the ph back up. My question is, does the TA really matter? Should we just adjust the PH every time it gets to 7.8 and not bother trying to get it down quickly?

 

[paigeag]

Bumping for afternoon crowd

 

[Richard320]

TA is the least urgent of the parameters.

As it says in the article on lowering it:

There are two reasons to lower your total alkalinity (TA) right away, because you want to slow down the rate that the PH rises, or if high TA is contributing to a high calcium saturation index (CSI) which puts you at risk of calcium scaling. You shouldn't lower TA just to reach a target number. Make sure you actually have one of the above issues before lowering your TA.

Just maintain pH and TA will come down. No need to go to any effort.