Out of whack

[cindyrose33]

Newbie here!

FC - 0.8
CC - 2.0
Ph - 7.2
CYA - off the charts
TA - 160

I can’t keep chlorine up because the CYA is so high, right? I need to drain to lower the CYA, correct? How much do I need to drain before refilling?

 

[mknauss]

Welcome to the forum!
You have fiberglass pool, so you cannot drain and refill conventionally.
100 is the limit of the CYA test, so you have to do a diluted test. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. Multiply the result by 2 for your CYA level. Let us know what you get.
What does the water look like? With a CC of 2, it is implying you have significant organics in your pool and will need to SLAM Process. But that can be done after a water exchange.

I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.

 

[cindyrose33]

Pool looks ok. Water is pretty clear but the fiberglass looks stained - even after a thorough brushing.

I redid the CYA test using a 50% pool/tap sample and the level stll comes back slightly over 100.

The pool store (my husband doesn't subscribe to the TFP method....yet!) claims it's because the phosphates are high. Based on what I've read here, it's because of the CYA level.

 

[mknauss]

That CYA pretty much means you need a full exchange.

You can exchange some water without draining.

If you place a low volume sub pump in the deep end and pull water from there while adding water in the shallow end (through a skimmer or into a bucket on a step so you lessen the water disturbance) you can do a fairly efficient exchange. That is assuming the water you are filling with is the same temperature or warmer than your pool water. If your fill water is much cooler than your pool water, then switch it. Add the water to the deep end (hose on bottom) and pull water from the top step.

The location of the pump and fill hose may change if you have salt water, high calcium, etc.
In my pool, with saltwater and high calcium when I drain, I put the pump in the deep end and hose in shallow end. The water in the pool weighs more per unit volume than the fill water from the hose.

Be sure to balance the water out and water in so the pool level stays the same. Also be sure your pool pump is disabled during this process. Once started do not stop until you have exchanged the amount of water you wish.

 

[mknauss]

The stains. Read this Stains in Your Pool - Trouble Free Pool

Have you ever used copper containing algaecide, shock, etc?