Adjusting pH and CYA

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gorocket1981

0
Jun 8, 2018
163
Montreal, Canada
Moved from here.

Texas Splash said:
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First, get a sock soaking with stabilizer to increase the CYA to at least 30. That should work for a while. While that's soaking, use muriatic acid to lower the pH to the mid-7s.
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Click to expand...

I don't want to hijack the thread but I am still newb and following your comment, I have 2 questions.

First, I used dry acid to lower the pH when required. I see many people referring about muriatic acid. What are the advantages and disavantages of using muriatic acid instead of dry acid? Pool store told me some years ago that muriatic acid was more dangerous for the water than dry acid.

Second question. You recommended to add stabilizer to increase cyanuric acid. I also have to do the same thing on my side. Since it is an acid also, will the addition of stabilizer itself lower pH and TA?

Thanks!
 
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Dry acid is sodium bisulfate. Adding it to your pool increases your sulfates and they can destroy metal and concrete. It is also more expensive than muriatic acid. In your area, with significant water replacement each year, and it appears, no metal or concrete in your pool, you can use the dry acid if you prefer.

CYA is a weak acid. It will lower pH a little bit. Use Effects of Adding Chemicals in Poolmath.
 
OK. If I understand then there is no disadvantages of muriatic acid vs dry acid?
I don't really care which one to use. Based on that, I understand that muriatic acid may be a better choice? I don't have that much metal or concrete in my pool but can the sulfates damage the equipment?
Maybe the pool store is not selling muriatic acid so it says that muriatic acid is worse for the water vs dry acid...
 
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Muriatic acid has the advantage as it adds only salt as a byproduct to your pool water.

Sulfates in general are not good. But I assume you drain 1/3 or more of your pool water each fall, so build up is less of a concern. And you should not need much acid as I would think your fill water is low in TA.
 
OK Thanks for the information.
After filling the pool, I initially had a TA of 34. The pool store said it was too low and asked me to raise TA to 140 which I did and it also jumped the pH from 7.6 to 8.0. That was before I begin to read TFP forums...
After reading your advice on one of my previous post and other similar advices on other users posts, I understand that TA of 140 is not required and not that good to maintain a lower appropriate pH. Pool store was probably right that TA of 34 was too low but 140 is too high. I don't know why that was the recommandation.
 
Pool store recommendations are based on the pool industry assuming you are going to use the acidic Trichor pucks for chlorination. With TFPC, we do not recommend the use of trichlor for daily maintenance, and thus you use lower TA levels and the pH is more stable and the water far more pleasant to swim in.
 
For adding CYA to the pool to get to the target of 30, the TFP directions says:
« To increase CYA via granular stabilizer, place the required amount as calculated by the Poolmath calculator into a white sock and place in the poolside skimmer basket. »

Do I just use any white sock that we have at home and put the granular in it or is this referring to a specific kind of sock that I need to get in a pool store?
 
Just a regular sock, the thinner the better. Since I can't seem to find any around here without holes, I use my wife's old nylon pantyhose or knee highs. Nylons allow the CYA to dissolve and disperse more quickly. If you have several pounds to add, use multiple socks/nylons and try to limit the quantity in each to about 1 to 1.5 lbs. If you run out of room in your skimmer, hang the socks/nylons in front of you pool returns. After the CYA soaks for a couple hours, you can go back and squeeze the socks to help the CYA dissolve. Keep the pump running during the process. Allow about 48 hours to get a reliable CYA reading.
 
I don't have a test kit yet. I am relying on 2 pool store to have tests done that are made with electronic spin disk in machine to do the analysis.
In the past 2 weeks, I added 4 pucks of trichlor in chlorinator and 500 grams of dichlor in water with the remaining chlorine in liquid chlorine. I backwashed 1 time for 2 minutes. Some rain but not that much.
Is is possible that the CYA level be 5 with all this? Since I have remaining trichlor and dichlor, my idea was to raise my CYA by using them. Did I miss something?

Thanks
 
If you had no CYA in the water previously, the trichlor and dichlor you added have raised your CYA by 20 ppm.

One test reliably measures that level, TF100. Pool stores consistently get CYA tests incorrect. Fancy machines do not automatically give correct results.
Get a test kit.
 

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I am not an expert, but you will lose some over winter, when exchanging or re filling. Another possibility is bacteria eating cya and turning to ammonia.
All that said...without a real test kit you dont know what cya is. So anything you do is a guess and could make things worse.
 
A CYA reading of 5 is invalid. It shows the ridiculous reading an automated machine provides. CYA is more accurate (though somewhat challenging to do) when tested the old fashion way, the disappearing dot.
Only way CYA leaves the pool in a short amount of time is via water exchange.
 
Entirely up to you, but I am not sure what is keeping you from getting a proper test kit. You can order a kit and have it shipped to a mail drop in the nearest US border town and go pick it up. Would make your life so much easier. If you fill up with fuel while there you nearly pay for the trip. Unless you live several hundred km away from the border.
 
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