High CYA but no algae yet. Can it be fixed without draining?

[DeleonsinDrip]

Hi all! First time posting here, but I’ve gotten so much valuable information that I knew I could come here for advice.

We are fairly new pool owners - 17K gallon plaster pool was completed in May so we had a great Texas summer with it. Water chemistry seemed right on for the most part all summer - high PH but I’ve heard that is to be expected for awhile with new plaster. We used Muriatic Acid frequently to bring it down. I’ll admit that since we haven’t been swimming as much we’ve slacked off on weekly chemical checks so now we’re in a pickle.

Sunday chemical check with the Taylor Complete (FAS-DPD chlorine) kit:
FC - 7
PH - 7.6
Alkalinity - didn’t check ??*
CH - didn’t check ??*
CYA - off the chart, above 100 where the reading stops.

Observations I have (please correct me if any of this is wrong):
-We’d been using the 3” pucks, which I know now are not recommended as they raise the CYA. It was at the recommendation of the pool builder. We have an automatic puck feeder (if that’s a thing?). I have since taken all the pucks out.
-We’d been using liquid chlorine from Home Depot when we recorded low levels and then also shocking with Clorox Pool & Spa Xtra Blue powder shock about once a week. We have full sunlight, no trees, so it was eating up the chlorine pretty regularly. I’ve now read that you shouldn’t use that as it raises the CYA. Is that right?

Yesterday I backwashed and drained down past the skimmers, refilled with fresh water and added about 1/2 gallon of liquid chlorine (based on the chart that says high CYA needs high chlorine levels).

Checked levels today:
FC - 9.5
PH - 7.2 (why did it go down so low?)
Alkalinity - 100
CH - 400
CYA - right at 100, so it has come down a little.

Based on all this, here are my questions...
Can we just continue to slowly dilute to bring the CYA down? Water is clear and no visible algae yet.
Should I do something about the low PH?

Sorry this is long. I wanted to include as much information as possible to get the most accurate responses. Thanks in advance!

 

[mknauss]

Welcome to the forum!

First -- do not use the Clorox Xtra Blue stuff - not only does it add CYA but it adds copper. Not good.

I would suggest draining and refilling at least half your volume. If you go in the small amounts you already did it will take many times the amount of water versus just getting it over with. You do need to be mindful if you have a shallow water table. Then you may need to do your small amounts.

Your 7.2 pH will rise with some aeration. You have relatively high TA, so it will drive the pH up.

Can you fill out a signature? See Pool School - Getting Started

Take care

- - - Updated - - -

You might also investigate adding a Salt Water Chlorine Generator. It will make your daily maintenance much easier next summer.

 

[DeleonsinDrip]

Thank you Marty! I tried to do my signature from my Tapatalk app on my phone but couldn't figure that out. I just did it on the computer. Maybe all the sanitation devices we have are keeping the algae at bay for now. We have considered a SWG but haven't researched enough to take the plunge just yet. We got so many mixed reviews on the salt deteriorating equipment and all the stone around the pool and the house. I know the maintenance is much easier though!

So, is "shocking" unnecessary if you keep the chlorine levels maintained, even in the summer? Or is it just that particular powdered shock that is not recommended? We've been told to shock in the summer once a week if there have been lots of swimmers or after a party or big gathering. Still figuring it all out!

 

[mknauss]

TFPC does not shock. By following [FC/CYA][/FC/CYA] you should never have an issue. If you do have algae, you SLAM Process.

The issue with the 'shock' method is that most of those pools have algae and can be non-sanitary. Follow the [FC/CYA][/FC/CYA].

Only in Texas is Saltwater an issue. Everywhere else, SWCG's are widely used. Especially in Australia, where they were first used for residential pools.

In your signature, you show both a UV device and Ozone device. Read this Alternative sanitizers and pools--The Truth!! Neither of them do anything for your pool. The UV simply consumes chlorine, and as you do get lots of sun in Austin, you already have plenty of UV. The Ozone is never big enough to really apply and only is necessary in high bather use conditions, typically indoors.

Take care.