High TA & PH - Purple Residue

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
rlsmith

High TA & PH - Purple Residue

Postby rlsmith » Mon 17 Sep, 2007 11:33

I have a fiberglass pool and through out the summer I have had high TA readings with stable to low ph readings. At one point early in the summer I had to ad muriatic acid every day for about a week to get the TA under control. Meanwhile my PH got so low that my pool guy was concerned about it corroding my heater elements. I got that under control but now I have high TA and PH with a purple residue showing up. I noticed this withing the last 24 hours. Chlorine will not maintain. I'm really concerned at this point that this purple color is resulting from copper metals that are corroding from my heater! I have friend within the same area that had a similar problem and went for about 4 weeks trying to correct it himself and found out that all this time his heater was getting "eaten away". Have you heard of anything like this?


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Postby mr_clean » Mon 17 Sep, 2007 12:38

I have a fiberglass pool and through out the summer I have had high TA readings with stable to low ph readings. At one point early in the summer I had to ad muriatic acid every day for about a week to get the TA under control. Meanwhile my PH got so low that my pool guy was concerned about it corroding my heater elements. I got that under control but now I have high TA and PH with a purple residue showing up. I noticed this withing the last 24 hours. Chlorine will not maintain. I'm really concerned at this point that this purple color is resulting from copper metals that are corroding from my heater! I have friend within the same area that had a similar problem and went for about 4 weeks trying to correct it himself and found out that all this time his heater was getting "eaten away". Have you heard of anything like this?


Can you show your chemical readings?
When you say "purple residue showing up" where? When testing chemicals? On the pool surface/walls?
rlsmith

High TA & PH Purple Residue

Postby rlsmith » Mon 17 Sep, 2007 13:00

My PH is around 8.0 and TA is off the test strip. The color on the test strip is out of range and is blueish. The residue is on the pool surface. I notice it on the pool steps or sitting areas, can't tell if its on the walls. The water appears real blue.
rlsmith

Postby rlsmith » Mon 17 Sep, 2007 13:02

By the pool surface, I mean under the water on the steps but I don't notice the purple color on the surface of the water.
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Postby mr_clean » Mon 17 Sep, 2007 14:02

The first thing I suggest is buy a good test kit like "Taylor" which will give better results and are not strips. Also take a sample of pool water to pool store in clean jar and have them test water. Once they test water for:
FC-Free chlorine
TC-total chlorine
CC-Combined chlorine
PH-
TA-
CYA-conditioner
CH-hardness

you will have a better idea of whats going on with your pool. It sounds like you have a high mineral/metal level in water because you say it looks blue and need to use a metal-remover in pool water. Depending on how high of level, you may need more than one bottle and then start using it as a preventative to keep levels down.
When you say you have a hard time maintaining chlorine in pool, what type of chlorine do you use?
Have you been adding alot to keep it high? The reason I ask is, a very high chlorine level can bleech out your PH/TA readings which will be wrong. Also if you use chlorine tabs, stop using them as they have CYA in them and with a CYA level above 100 it will make chlorine less effective. The only way to fix would be to empty some pool water and refill. A good CYA level is 60-80, also when CYA level gets to high the pool walls can start getting a purple ring on them.
rlsmith

Postby rlsmith » Mon 17 Sep, 2007 15:51

Mr. Clean,

I appreciate your knowledge and help.

I have been using chlorine tabs (on a minimal basis 2-3 at a time until almost dissolved) in addition to having to add shock on a weekly basis to keep it up. At the moment (as of today) I'm putting in PH minus (1.5-2 lbs) every six hours until I see results of the TA come down. But, like you are saying if the chlorine is bleaching out my PH/TA readings then I better lay off adding anything until I get the water tested?? Correct?The biggest concern I have at this point is that I do not want to jeopardize damaging my heater any more than it may already be. My question is, how long does it take to totally ruin a heater? From the little you know as of right now, have I done that already?? Also, adding more water (which ours is high in akalinity) will only be fixing the CYA problem if there is one, if there isn't will adding more water help eleviate my other problems or worsen them?
rlsmith

Postby rlsmith » Mon 17 Sep, 2007 16:25

I also wanted to ask another question........

Should the pool be in balance before adding any metal free product. I have a couple 32 oz. bottles of Natural Chemistry's product Metal Free?

Thanks.
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Postby mr_clean » Mon 17 Sep, 2007 16:36

What is the PH reading you think was low? When you go below 7.2 you can start having problems with heater exchange over a period of time, the lower the PH the faster the problem can become worse. How long has PH been low?
If your CYA is over 100 then emptying some water and refilling is only choice to fix it and yes TA would most likely be effected if ground water TA is high.
When adjusting PH/TA you can use aeration to help adjust PH back up and not effect TA. You can look at another post in this PH & total alklinity area it's under really HIGH alkalinity for a long time....
chem geek explains it well and has link to another page you can save it in favorites
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Postby chem geek » Mon 17 Sep, 2007 16:38

The TA lowering procedure is described in this post.
rlsmith

Postby rlsmith » Mon 17 Sep, 2007 17:52

Mr.Clean,

Earlier in the summer when it got low it was in the 6.2 - 6.8 range for probably a week. But the PH being low is not the problem now, on the contrary. I checked the water just prior to this email and the purpleness has increased all over. You mentioned previously that high chlorine may cause misreadings on TA/PH. Maybe, my PH reading is totally off creating this purpleness from the heater?? What about a metal called manganese, possibility??

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