Enless Pool-Corrosion Issues PLEASE HELP

Jeffm · Postby **Jeffm** » Thu 23 Apr, 2009 10:24

Well, I brought another sample in to work to have the Lab confirm my home readings. I use the Taylor test.

My readings: 7.6 pH 170 TA 225 CH

Lab 7.6pH 115/120 TA and 175 CH

I use the Taylor tests, guess I need to replace reagents. Also looks like my chemistry is a little low. I'm thinking I should shoot for about 320 on the CH.

Jeffm · Postby **Jeffm** » Sat 25 Apr, 2009 11:54

Update on chemical questions:

I currently have a FC level of 1.5 and TC level of 2.0.
I'm going to guess that's pretty normal, but I don't do the TC check often.

I did a CYA check and am at about 70 ppm. Again, I don't do that check often.

For chlorine I have been using "Pool Season" brand Granular Stabilized Cholorinator.

Active Ingredient is Sodium Dichloro-S-Trizinetrione Dihydrate
Available Chlorine 56%

Postby **chem geek** » Sat 25 Apr, 2009 20:57

Do not ever use Dichlor unless you intentionally want to increase the Cyanuric Acid (CYA) level in your pool. The following are chemical facts independent of product concentration or water volume:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm.

Your pool has a much higher risk of getting algae if the FC is low relative to the CYA level, especially if it's below 5% -- so at 70 ppm you want at least 3.5 ppm FC unless you plan to use a supplemental algaecide or phosphate remover at extra cost.

Jeffm · Postby **Jeffm** » Sun 26 Apr, 2009 08:39

So, really....it wouldn't be a bad idea to replace some of my water, and drop the CYA level down?

As far as I know, there's no other way to drop the CYA down.

Postby **chem geek** » Mon 27 Apr, 2009 02:07

You are right that CYA is only lowered (in a controlled fashion) by dilution. You could live with the higher CYA if you maintain a higher Free Chlorine (FC) level, no lower than 3.2 ppm at any time (and I mean ANY time) with 5.2 being more of a minimum target. If you lower the CYA level, then you can have a lower FC level. Otherwise, to have lower FC at 70 ppm CYA you'd need an algaecide or phosphate remover to prevent algae growth.

Jeffm · Postby **Jeffm** » Mon 27 Apr, 2009 07:57

Okay, well I drained about 1/2 to 2/3. Figure I'll hold the Cl level between 3 and 5 for a few days while I balance the other chemical levels, then do a CYA check and come up with the proper range.
All of the stainless is still outside the pool for now.

Jeffm · Postby **Jeffm** » Mon 04 May, 2009 14:18

Well, I put all the stainless back in yesterday.
It made it through this morning with no corrosion, haven't run anything yet.
Pump will kick on this afternoon for a few hours, no heater.
If all looks good, will try to run the heater tomorrow. That's my big concern, it may sound silly but one theory I have is there is something electrically screwed up with the heater inducing a current into the water.

Keep your fingers crossed.

FC is 1.0ppm
TA is 130 (I'd like to lower it a bit)
CH is 375 (It shot up when I drained and refilled, I really think the difference is the well water when the ground is frozen or unfrozen)
pH 7.8. Yea, it's a bit high. I'll hit it with some muriatic, and lower the TA just a hair, and drop the pH down to 7.5