Low pH

[CarlD]

These are from March 18 from yes....the pool store analysis :
chlorine was 0 - I have obviously fixed that
ph was 7.8 - that too is now in the normal range according to my test kit
Acid Demand 1
Total Alkalinity 80 ppm
Calcium Hardness 325 ppm
Stabilizer 50 ppm

This is all they tested for. We had seen the water "foaming" and were told to next time ask for a TDS test. I am not sure we will be going back there next time so...the ranges they gave for the above were all fine for what we need (according to their analysis) except the pH was then high and of course there was no chlorine...

So any suggestions at this point? The pool is testing fine for both chlorine and pH now (my own test kit) but that is all I CAN test for. The water is crystal clear...

Acid Demand and TDS are useless tests just to impress you. Foaming could be the start of algae--shocking with bleach should fix it. If not, something else is causing it and Ben or one of the other moderators can help better than I can.

Total alkalinity is a bit low--the lowest end of acceptable--and if you lowered your pH it's gone even lower because T/A moves with pH. Add a pound of Arm&Hammer baking soda to fix it. I like it to be between 100 and 125. In a vinyl pool, you can go as high as 180 without worry.

CYA is at the maximum level that I like--50ppm. I would only chlorinate with bleach or liquid chlorine from now on. Your only other choice is Cal-Hypo--but your calcium is 325ppm, which is fine. Buy you don't necessarily want it too much higher, and Cal-Hypo will raise it. Stick to bleach.

So your CYA is high (but OK), your TA is low (probably too low)--and you have some foaming. You'll need to raise TA, shock your pool, then keep your regular chlorine level at a minimum of, say, 5ppm (I'll check that). and you should be OK.

[howbout]

Well, that test was done back on the 18th. Like I said, since then we have treated the pool. At the time we did have algae. So those numbers really aren't anything you can work with NOW. The pool has been shocked,the pH brought up, etc. I think now from my tests and the way it looks everything is in shape. And don't forget it is NOT a vinyl pool, it is an inground pool!

[CarlD]

Well, that test was done back on the 18th. Like I said, since then we have treated the pool. At the time we did have algae. So those numbers really aren't anything you can work with NOW. The pool has been shocked,the pH brought up, etc. I think now from my tests and the way it looks everything is in shape. And don't forget it is NOT a vinyl pool, it is an inground pool!

OK, but NOTHING you have done will lower your CYA--if you shocked with DI-Chlor or Tri-chlor it could go up. T/A will go up if you raise pH, and down if you lower it further.

Inground pools can be plaster, tile, concrete, gunite, fiberglass, or, yes, vinyl. Lots and LOTS of I/Gs have been vinyl for well over 35 years now (as a 15 year old kid I took care of a neighbor/friends's I/G--vinyl lined.)

So, ASSUMING you have concrete/plaster/tile, you absolutely must keep your T/A between 90 and 125--80 and 130 should be your trigger points to act. You must also keep your calcium hardness between 200 and 400 ppm--no lower or the water will leach calcium from the walls, no higher or you'll have scaling.

Keeping with that assumption, you have lost flexibility re: T/A and Calcium, but you gain it in pH. Where going below 6.9 is very dangerous in vinyl, you are much safer and could go down lower without fear (but I wouldn't because the water would be too acid). In an algae situation, you can safely raise chlorine levels FAR beyond the shock level for you CYA without fear of damaging or bleaching your liner--levels of 50 or 60ppm which would bleach a liner are not a problem. Also, muriatic acid poured into the water is less likely to damage the walls if it gets close to them. Muriatic will cause a vinyl liner to curl, soften and melt if too much actually contacts it--Muriatic Acid is best diluted and added to the deepest part of vinyl pools, slowly, so it can dissapate and not form a "slug".

New plaster/tile/concrete/gunite pools tend to go through a curing period. During this time your pH will keep rising and you'll be adding Muriatic all the time. This is normal.

Good luck with it.

[VickieC24]

I think the clarification is that you have an inground pool that is NOT vinyl lined. (Maybe it's cement?) I have an inground pool with a vinyl liner.


Vickie

Well, that test was done back on the 18th. Like I said, since then we have treated the pool. At the time we did have algae. So those numbers really aren't anything you can work with NOW. The pool has been shocked,the pH brought up, etc. I think now from my tests and the way it looks everything is in shape. And don't forget it is NOT a vinyl pool, it is an inground pool!