Why do vinyl chemical levels vary so much on other websites

[Wheelie]

Hello,

TFP gives the following levels for a vinyl pool (no SWG):

with Bleach
FC 3-7 (See chart)
pH 7.2-7.8
TA 50-90+
CH 0-350 (Don't add)
CYA 30-50

When I refer to other websites, particularly liner specialists, the range is very different:

pH	7.2-7.6
Total alkalinity	100-150 ppm
Calcium hardness	200-300 ppm
Cyanuric acid	30-100 ppm
Free chlorine	1-4 ppm

Does anyone know why the advice is so different?

I tested my pool yesterday and my pH is around 7.8 to 7.9. TA is 90-100 so I was planning to lower the TA slightly before lowering the pH. But according to other websites my TA is actually low.

I'm thinking I'll just lower the pH to 7.6 and not worry about the TA for now.

Thanks,
Keelie

 

[pabeader]

The reason is that other sites just reiterate what the industry has said since the 70's. Here at TFPC we use real world, peer reviewed values that have been tested and verified by 10s of thousands of pools. Backed by solid chemical studies.

- - - Updated - - -

Here is an example that explains about lowering TA: Pool School - Lower Total Alkalinity

 

[pooldv]

Adding acid to lower PH will also lower TA anyway. We have lowered our TA recommended levels over the years as we have found through feedback from many members and personal experiences of many contributing members that the pH is much easier to manage when TA is lower. With TA at 120 or higher it will continually push your pH up requiring frequent acid additions to lower PH which will in turn lower your TA and then you'll need to add baking soda to raise TA which will push your pH up, repeat, repeat, repeat. There is no downside to having TA somewhere between 50 and 70.

 

[Wheelie]

Okay thanks, so I should lower my pH to 7.2 and then let it rise back up by itself, then retest TA to see if it's dropped?

 

[needsajet]

Yep, that's one of the ways to lower TA. Dropping down to 7.0 each time will do it faster. This is the medium speed way to drop TA.

Or you can just add acid when you see pH over 7.8 and drop your pH to 7.6 each time. Your TA may not drop noticeably, or will fall slowly.

Or you can use the procedure mentioned, and lower TA quickly. Lower TA will slow down the acid additions.

TFPC chem levels will give you long liner life. If you need tests to protect warranty or something like that, you can run low CYA (say 30) and FC at 3-4 ppm, or just grab a pool store test when you have those levels, and get it back to best levels after you have that piece of paper in the drawer. Keeping TA in the range you mention from liner specialists or pool stores will keep you on the acid/buffer roller coaster as mentioned.