CYA off the "best guess" chart. Advice?

[duraleigh]

Hi, Scott,

I'm with Kurt....you've got a great handle on understanding your pool chemistry...wish I had learned that fast.

If you do 25% refills, it will take 7 of them to get your CYA below 50. If you can tolerate a 50% refill, you can do it in three.

I also assume that TDA is TDS (total dissolved solids) and that's a little high as well. Drain and refill will sove both issues.

You're off to a great start...enjoy your pool!

Dave S.

[mwsmith2]

Also, if you want some overkill in figuring out the dilution of your pool, you can grab my calc in my sig. There's a dilution section in there that you can put in the size of your pool and it will tell you a percentage drain to get to a number that you want. Either that or you can fiddle with the numbers to see where you would end up from a partial drain. Either way, it's something to play with.

Oh and there's another nifty way to do a water change without floating your pool. What you need is to source a HUGE sheet of plastic. Throw it over your pool. pump water out from under it with the pool pump, and refill on top of the plastic. As you pump out from under and refill from the top, the plastic will sink down into the pool. The plastic will keep the water separate, and you can actually change 100% of the water in one shot this way, if you can find a sheet of plastic big enough. This is a trick that vinyl pool owners use to change water without ruining the water.

Michael

[geoeremite]

Thanks for the great feedback, that helps a lot. Yes, I meant that TDS was 1000.

I'll probably do the 25% at a time solution, although the plastic trick is a really neat idea. I figured out last night that the water doesn't cost any where near as much as I feared, which is also reassuring.

Michael, I've seen bleachcalc and wanted to give it a try (sounds great), but I guess that's one of the (few) drawbacks of being a Windows-free household.

cheers,
Scott

[dontremember]

Michael, I've seen bleachcalc and wanted to give it a try (sounds great), but I guess that's one of the (few) drawbacks of being a Windows-free household.

BleachCalc runs just fine in Linux with wine-0.9.11. Dunno about non-x86 systems, though...

Ralph

[PoolDoc]

Hi Scott;

Given that you have extremely high CYA and 7 year old water, I'd definitely go with water replacment. 'Used' pool water does build up residue which tends to make it harder to work with -- things like phosphates, nitrates, and who knows what else.

It's this residue that is behind some of the push to measure TDS, despite the fact that TDS meters (really, conductivity meters) can't distinguish bad 'residue' from benign ionic content, like salt.

Replace as much as you can at one time -- you won't get nearly the effect from replacing 25% 2x as you will from replacing 50% one time.

But, you've got to be safe and draining your pool can definitely destroy it, depending on type and situation.

Ben

[geoeremite]

Thanks Ben. I've already completed one drain/refill cycle and am midway through the second. Drained off about 28", which I'm estimating is about 40% by volume (funny how that works). Drains pretty slow since the waste valve is a standard hose bib and there are no valves in the pump/filter/heater area that can be used to force more water to waste (would have gone faster before cleaning my filter when the back pressure was 35psi rather than 14, ).

I figure 4 passes like this and I should be in good shape. I did verify that my CYA dropped to around 150-175 after the first cycle.

[geoeremite]

Four passes later, it looks like everything is in good shape. Here's the numbers:

FC 5.0
TC 5.0
Ph 7.2
TA 100-110
CH 200-225
CYA 20-30
TDS 400

(Pool store numbers that match the values I was able to independently measure, including FC,CC,CYA.) CYA could come up a hair, but I think that I'm not going to worry about it for a bit. Was glad to see that it held its FC overnight without issue.