New house, high CYA

[nopoolstore]

I've been out of the pool maintenance routine for a few years. I just moved into a new house with a pool and am getting back into the routine of doing things right and having a nice pool.
Previous owner had pool "service" that was paid for until end of May. I spoke with the pool girl and it's obvious her job is to clean the skimmers and fill the floater with tabs. She knew nothing else, answered most my questions with I don't know, or reffering me to call the owner for answers.
My test kit just arrived yesterday and pool service has expired so now it's my turn.
My fc is 4.5, CC 0.5, but CYA is off the chart. Using the tf100 kit's graduated cylinder I fill about halfway to the 100 mark and loose the dot. The cylinder's marks are not linear so halfway to 100 must be something like 300??
I am assuming that the pool service has been using ONLY tabs for chlorination and now my pool has become way over stabilized?
So question I have would be if I need to drain water to get rid of the high cya, how much should I estimate to drain?

 

[mknauss]

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.

Do a CH test too. Between the CYA and CH level we can advise how much to drain. Start determining where the water will go that you drain. Also whether drain is safe (high water tables?) or if you will need to exchange.

 

[nopoolstore]

So testing Cya with 50% tap water as you recommended. Comes out just below the 100 mark, so multiply by 2 and get a little over 200.
My CH tests at 300. I tested my tap water and it is 175 or 200 (depending on your opinion of when it changes to blue)

 

[Texas Splash]

Unfortunately, the only thing you can do to lower CYA is water exchange. Depending on your DE filter (bump-plunger or multiport), you may have options of how to exchange some water. But for a good frame of reference, a 50% water exchange will lower the CYA by 50%, so you'll have to go a bit lower I suspect. While some folks will rent a sump pump for quick efficiency, others will do a continuous water exchange by slowly removing water from the deep end while pushing new water into the shallow end. When Marty returns to follow-up, he'll fill you in on that process. But a water exchange will be needed to lower that CYA to something more manageable. But hey, it may help the CH a little as well.

 

[santacruzpool]

Sounds like at least a 50% water exchange/drain is what you need.

Marty and Pat are the TFP experts and are great people to advise you.

 

[mknauss]

You can exchange some water without draining. You should target a 75% exchange.

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.

 

[nopoolstore]

I apologize for my rookie style question, but this is my first in ground pool. I've had numerous large Doughboys in the past so I'm learning the slight differences with a plaster in ground.
With the above ground pools, I could drain dang near all the water if need be, just leave enough to keep liner stretched in place.
So based off of the exchange methods you guys recommend, I assume that draining half the volume of my pool is not a good idea? Is that for fear of it popping out?

 

[Oly]

Right, if you have any water table issues then draining the pool may result in "floating" your pool shell out of the ground.
Check my first thread in my signature as I has a similar situation but I knew I did not have a high ground water situation.