Draining and refilling 12,500 gallon gnite pool

Hello forum,

I've been having an ongoing issue with algae, and up until I tested my CYA with my 2006C kit, i had no idea it was as high as it really is (120 ppm). The test strips were wrong.

I'm going to drain and refill my gnite pool. I read the thread for the person with the 33,000 and the 15,000 fiberglass, but have my own questions...

1. How much stabilizer can i expect to add to get a CYA reading of 30 ppm, and when do i add it during the refill?
2. I have some staining on the pool floor. What can i use to get rid of them when the pool is empty (I've read Vitamin C?)
3. Might as well change my pool bulb, too. Is there a special bulb that i have to use, or can i replace it with a CFL or LED bulb. I'm going to change the gasket as well.
4. When do i address the Alkalinity and Calcium?

Sorry for the lengthy post. It's kinda like a big deal considering i've only had the house/pool for 3 months now... Noob! Thanks in advance!

Miles

Hi Miles, and welcome to the forum.

Just a thought---you don't have to drain the pool just because your stabilizer is high--you can always just up your baseline chlorine levels to compensate for it...take a look at the "best guess chlorine chart" link in my sig for more details on that. However, if you choose to drain your pool, be aware that if you're not careful you can actually float the pool out of the ground!! Hopefully Ben or one of the others will be by soon to address the rest of your questions, but I just don't want you making any hasty decisions that you'll regret, when draining is NOT your only option!

I'm familiar with the "Best Guess" Chart, but aren't there drawbacks to keeping the chlorine that high? I have a 1 1/2 year old. And can you float a concrete/gnite pool? I though that was only relevant to liner pools? Also, does chlorine consumption go up when you're maintaining that high a level? Sorry about all the questions, but i'm trying to make sure i do what's best... Thank you for the inputs and answers!

yes you can float a concrete pool- there are some barges made from concrete, so it will float in the right shape, and a pool has plenty of empty volume; less likely than fiberglass, but can happen especially if water table is high/ground is wet.
I would consider a half drain and fill as a potential time and money saver- if you're confident of the 120 number, 1/2 would be 60 and not a bad place to be for CYA, and then only have to replace 1/2 chemicals.
vitamin C does clean up some metal stains
As you add water, you can add bleach pretty much as soon as water covers bottom- maybe 6 inches, just keep it stirred manually.
I would add calcium once you get water circulating
don't think I'd mess with alk until completely full, and you see what the pH is doing; alk is pH stabilizer- if pH is stable, don't need alk.
also, Borates can work well as pH stabilizer, and also helps water be crystal clear!

At higher CYA levels, you usually don't have to add chlorine as often.

Well, Cool Beans... If I'm understanding everyone correctly, I really don't have a need to drain my pool with the CYA being as high as it is as long as i follow the best guess chart? My next question is, is there a kit other than the 2006 that i could use for regular, quick chlorine measurements, or am i always going to need to use the FAS-DPD kit for chlorine measurements above 10 ppm. And last question, with the chlorine stabilization being what it is, should i shock every two weeks, and will it take days for the chlorine level to reach a reasonable level again? Thanks again!

Yes, you can run a high CYA pool as long as you run chlorine levels per the Best Guess chart.

You'll have to use the FAS-DPD to read high chlorine levels. Other kits won't read that high. (You can always buy refills for the FAS-DPD powder and R-0871 without having to buy another whole kit.)

It is not necessary to do routine shocking. As long as you always keep your chlorine levels within the correct range and don't have any CC reading above 0.5ppm, shocking really isn't necessary. (I seldom ever shock my pool). In a high CYA/High Cl pool, it does take longer for cl to come down. Just be diligent about your chemistry and you won't need to shock.

Thank y'all so much for your help!! This forum is worth it's weight in GOLD!! (Virtual of course.)

Miles