Draining pool

Dirk said:

Removing only about half the water would bring your CH down to an acceptable level. That would bring your salt down to about 2350, also acceptable. Tile blasting can be done without draining the pool. Tile work could also be done without draining the pool all the way down, if the contractor was up to the challenge. So technically you don't have to drain the pool completely. Fool around with the calculators in Pool Math and you'll see what I mean.

Draining a pool comes with risks. The water is part of the structure. It's weight and pressure, or rather removing it all, can affect your plaster. That's more true of older plaster, but even newish plaster that has not been maintained properly can be damaged by removing the water. Mine was ruined by that, and it was only about four years old. Primarily due to really poor pool water maintenance before I owned the house, and a really bad acid wash, but the missing water contributed. Also, a pool can float right out of the ground when it's even partially empty. Do you know where your water table is?

Short version: the longer a pool is empty the greater the odds something bad can happen. Others here know more about that than I do, but personally, I'd never drain my pool if I didn't have to. I thought I wasn't going to, ever, but my CH got away from me, so I replaced 3K. It was only 2/3 full for a few hours, but even that made me nervous. I'm sure some pools can go many weeks without water without any issue. The problem is, you'll only know for sure how yours will be affected afterwards!

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mknauss said:

Salinity in the pool water has no effect on pH, TA, or FC levels.

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Dirk said:

@mknauss, what do you think about that. It's news to me... Marty, you must have read my mind as I was typing!

One way to avoid the concern altogether is to do a no-drain exchange. The level of the water never drops, but there's a way to wrangle the bad out while the good comes in. You'll use more water to do it, but water is cheaper than a catastrophe. Now the chances of your pool floating are very slim, especially at the end of summer. But slim is not none, so a little due diligence is in order. Call your local public works department. If they don't know the local water table, then maybe they'll know who does. Phone calls are even cheaper than water!

No drain exchange is a few paragraphs down the page. Though I don't think you can ever get down to zero salt with that method.

Draining - Further Reading

www.troublefreepool.com

Another solution is to buy a salt water chlorine generator and convert your pool to a salt water pool. You will absolutely LOVE the convenience, and the feel of the water, and you can stop thinking about how much chlorine to pour in. SWGs require around 3000ppm salt, so In your pool you'd only need to exchange about a third of the water. I'm not sure anyone has done the math since "inflation," but not that long ago the long-term total cost of a SWG is about the same as the cost of the liquid chlorine you'd buy if you didn't have one. Except you won't have to lug it from the store anymore!

With an SWG, your salt level will accumulate less, because it's the liquid chlorine's byproduct that is adding salt. Muriatic does, too, but you'd be halving the source. I use a lot of acid but never have too much salt. In fact I have to add some every so often.

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Dirk said:

FC levels and acid demand vary a great deal throughout the year, definitely due to air and water temperatures, along with the amount of sunlight on the water.


We'd have to do some math on that. One of your driving water replacement forces is your CH level. That's coming in from the fill water. I have the same issue. I greatly reduced CH-rise by filling my pool only with the water from my water softener (near-zero CH). I've only had to exchange once since I started doing that, just this year, after about four years I think.

Even if you can control the salt level, you'll have to do something about that CH, too, to minimize water exchanges.

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Dirk said:

There are mobile RO filtration systems that can be brought to your home. I think they'll get rid of the salt, though it's not clear what they do with the stuff they suck out of your pool. Might be worth a call to see if there is one that can service your area. Here's an example, and they're kinda close to you. Maybe they could do it. Or know who could.

Reverse Osmosis For Swimming Pools!

www.poolwaterrecycling.net

My city doesn't want my pool water anywhere either, though they told me I could let it drain to an empty field. Which I happen to have behind my house. Anything like that you could use?

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