Red eyes and white deposits at waterline

[Meixnerm88]

I am pretty new at managing my pool, and have a couple symptoms I would like help with.

Pebbletec floor
SWG
15,000 gallons
TA 120
Temp 86-90
PH 7.6-7.8
CYA 100 (even though I drained the pool 3 months ago)
FC 7.2 (I am keeping this high because of high CYA level)
CC 0
Taylor K-2006C test kit
CH 300 (though even with workaround for color turning purple instead of blue, it still turned purple instead of blue)

Seeing red eyes and calcium deposits at waterline. Also had a couple algae outbreaks in last few weeks, but I had let the chlorine level drop.

Very hot here lately. That, with pretty heavy usage, has been making managing the chorine level challenging.

I have used scaletec before but not religiously. Should I?

Is it important to use algaecide and clarifier religiously?

Thank you very much for any advice!

-Mark


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[topher]

what are you using for chlorination? your CYA level may be WAY higher than 100.. have you tried the dilution test for CYA?
if your using pucks or tabs, you may be adding more and more CYA to your pool causing you to need REAL high levels of FC to keep the algae at bay. with a CYA level of 100 you require a minimun of 8ppm of FC. this may be why it is going green on you.

algaecide and clarifier are not needed.
if you have not done so yet, read through pool school.

 

[JasonLion]

As topher suggests, the high CYA level really jumps out at me. How did CYA get that high? With a SWG, you shouldn't have the usual cause of rising CYA levels, ie trichlor tablets.

You are right on the edge of calcium scaling. With the numbers you have right at this moment you are fine, but it is easy for PH to go up when your TA is too high (as yours is), and that could easily push you into scaling. I recommend lowering PH to 7.2 right now and each time it gets up to 7.8. That will lower TA a bit over time and give you more headroom before scaling can happen.

 

[Meixnerm88]

Thank you for the responses. Some more information:

1) I have 2 different CYA test kits (one sold by Pentair, the other is part if my Taylor k-2006C) that both use the disappearing black dot method. Both read 100.

I used chlorine tablets before replacing my 5-yr-old SWG. Maybe for 3-4 months. Probably where my CWA came from.

2) I struggle to keep my PH under 7.8. It seems like I use a Lot of muriatic acid, sometimes multiple times a week. But I used the acid demand test to verify the doses.

3) my next to-do is to more closely estimate my pool volume.

4) I also read about aerating after lowering PH to try to get TA down. We use waterfalls and jets a lot so that is maybe why my ph keeps going up. But my TA stubbornly sticks at 120. I will take the PH down to 7.2 now and in the future. Is there a TA number I should be aiming for?

5) does any of this info explain the red eyes?

Thanks again very much for giving me concrete advice.

I welcome any additional feedback. I have studied Pool School and refer to it and its references often.

-Mark

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[ping]

You want the CYA to be 80 and anything that measures at 100 could be a lot higher. Try adding half pool water and half tap water for the water sample and then multiply the result by 2 to get a more accurate number for the CYA.

The scaling is caused by the pH rising too high, you need to control it with acid. If you want to actively reduce the TA, we suggest 60-80, then acid additions along with aeration is the way to go. SWG users should keep the TA in the 60-80 range and this will help keep the pH from rising so fast.

How long are you swimming before you get red eyes? If you swim long enough you will get red eyes no matter what if you don't wear goggles.

Keep adding the reagent when the CH test turns purple, it should turn blue with more drops. Mine usually takes 10 more drops before I see the blue color that the test wants.

 

[Meixnerm88]

Thank you for the replies. I read somewhere that one needs to subtract out the buffering effect of high CYA levels when considering whether the measured TA is too high. Factoring that in puts the calculated TA not due to the CYA in the 80 range. I also noted some disagreement on this topic in my reading.

I will try the diluted CYA test.

Thanks again,
Mark


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[Meixnerm88]

The diluted CYO test calculates the CYA level between 90 and 100. Does this confirmation trigger any ideas?

I am already lowering my PH to 7.0-7.2 and aerating when PH gets above 7.5.

Thank you,
Mark


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[techguy]

Wait... were the results 90-100 with 50-50 pool/tap ... or was the result 45-50 with 50/50 and multiplied by 2 to get you 90-100 CYA

IIRC, this a little high for a SWG pool. If you can cost effectively drain 10-20% of the pool and re-fill, your FC will have more effectiveness and your SWG will not struggle to produce enough FC.

 

[Meixnerm88]

The result with diluted water was 45-50 and thus confirmed the prior reading of 100. So the goal is 80 CYA? I understand why replacing 20% of my water should take the 100 reading down to 80.

Thanks,
Mark


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[techguy]

I will let one of more senior SWG gurus confirm. I am a chlorine guy.

 

[jblizzle]

Having the higher CYA will actually protect the FC more and should make the SWG work less hard.

The problem with the high CYA is when your water develops a problem and thus the shock process is required. Even having the CYA at 70-80ppm for a SWG will be a headache if the shock process is required.

 

[Meixnerm88]

Will it be a problem to shock because I would have to get the FC level really high to do the job, and thus wait a long time for it to get back to safe levels?


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[jblizzle]

No problem. You are safe to swim at FC level up to shock level with no worries. Most of the industry does not understand the CYA/FC relationship.

 

[Meixnerm88]

Can you please point me to a good CYA/FC relationship explanation?

Thank you!


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[jblizzle]

Not off the top of my head. Search for something like "safe chlorine levels" and look for chem geek posts