Can I drain and power wash my IG plaster pool?

[Technigogo]

I have a 30k gallon plaster pool. Over the winter, pump started leaking on the bottom of the casing so I turned it off. Time got away from me and now I have a green mess.

I am 4 days into SLAM and it is clearing -BUT- I found lots of leaves still in the bottom and walls are stained. Actually, we have owned the home for 8 years and the 30 year old pool has always had stains.

I would like to drain the pool, remove all the debris, power wash to remove staining and refill.

I'm in Austin, Texas. How long can I leave it drained to work on it? I'd like to drain it now (Tuesday) but I can't get to the working inside of it until Saturday. Plus, if I need other repairs, it may take week or two to line up professionals.

Can I safely power wash the pool? Low power? Is there any chemical or spray treatment I can use to reduce the staining?

I don't want to spend the money on replastering yet so I'm looking for DIY solutions here.





This shows the staining on the step and around the edge where you can see the plaster.



This is a close up of the staining on the step.

 

[pikeman]

Hi. I did this a few years ago with my pool. It's half your size, so to get a fast drain consider renting a pump. I used my 1600psi washer and was careful. No issues, just used water.
Drained one day, washed, refilled and running again by morning of third day. I didn't allow pool to dry out.
This might be the best way to proceed if you've got a slimy lagoon.
Pete

 

[Technigogo]

Thanks for your reply, Pete. Good suggestion on the pump. I did that last time I drained it but since then I have installed the 3HP pump and individual valves on my suction lines. This allows me to just suck from the bottom drain and I think I can empty 30,000 gallons in about 6 hours.

Anyone else with some more feedback on leaving the pool empty for a week or so? I suspect there will be some places that I may want to consider plaster repair and such. Since my pool is built into the rocky soil of Central Texas, I'm wondering if I really have to worry about float issues. The fact that it hasn't moved in 30+ years I thought might help the case as well.

Also, anybody with input on using any chemical to remove or reduce stains in the plaster while it is drained?

 

[JoyfulNoise]

Do NOT leave it empty. If the plaster dries out too much it can easily crack. There is currentky tens of thousands of pounds of water in the pool applying mechanical pressure to the surface that holds it in place. The water is also cool and doesn’t allow for much in the way of thermal cycling. If you empty it and leave it that way, the plaster will dehydrate, change temperature rapidly and have no inward mechanical force on it. That a recipe for disaster.

Those stains are not likely going to be removed with a power wash. Your plaster is old and stained and there’s little to do about it with a power washer. You are better off SLAM’ing the pool, getting the water cleaned and balanced and then investigating possible stain removal techniques.

Draining a pool, while a favorite of the pool service/pool store industry, is rarely ever necessary.

 

[Technigogo]

There is actually another reason for the drain. To get started on this project, I dumped in Clorox 6-1 Shock that I picked up from Costco since bleach has gotten expensive there. I didn't read the ingredients until too late and then saw that it contains copper. I'd rather not have that in my pool. That and the fact that water is super cheap where I live. I can drain and refill my 30,000 gallon pool for $167. I spend more than that on Chlorine and DE with the SLAM, not to mention the time consumption of babysitting it for days on end during a SLAM.

 

[lightmaster]

Has it rained recently there? Do you know how high your water table is? When you remove all that water weight, your pool can very easily float if the water table is high. Think of a cup in your bathtub, filled with water, it easily sinks into the water in the tub. But when you remove the water from the cup, it takes a lot more force to keep it in the water and not floating on the surface. Your ground might appear dry, but when you dig a few feet down, you can easily hit water and start seeing your 4 or 5 foot hole filling with eater at the bottom. I don't know the extent of damage floating a plaster pool would cause, but I imagine it would be quite extensive.

- - - Updated - - -

If you're really set on draining your pool, dig a hole 10 feet away from it that's a foot or 2 deeper than the pool and see how far down you get before you start hitting water.

 

[JoyfulNoise]

Every 1lbs of that shock added increases copper levels by 0.04ppm. So, depending on how much you added, draining might still be unnecessary or, you might only need to do a partial drain. Copper only becomes a problem when the levels go above 2-3ppm and the pH gets really high. Even if you completely drain the pool, you'll still have to SLAM it as you'll never get rid of all the algae. However, draining then refilling & SLAM'ing should go faster.

Good luck.

 

[Technigogo]

My yard is about 30 feet above a bone dry Slaughter Creek which is about 50 feet beyond the swimming pool. Slaughter Creek is all bedrock limestone. Would that tell me the water table?

In Texas, we only talk about water table when it comes to drilling a well ...that is usually hundreds of feet.

 

[Texas Splash]

Really lots of very good advice above. Only 45 minutes from you, my soil is that sticky, black gumbo stuff that gets socked, then dries-out and cracks, shifts, etc. A royal pain in the rear. Now in your area you might be in that bedrock belt, but you'd have to ask someone familiar with your soil and engineering. Maybe the county office can help? When in doubt, I would do as others recommended and at the very least consider leaving some water in the bottom - maybe a couple feet or so at least. That should resolve any copper concerns and give you a good look at the exposed plaster to see how bad it is. You might also contact a professional who can give you a quote at the same time. If you end-up having to have the whole pool replastered, then the contractor you hire should be responsibly for verifying the shell stability or taking such precautions. Tough call really based on the age of the pool and such. Even Pete's experience in post #2 sounds attractive, but I'd want to know about the soil first. Plus, your pool's plaster might be more fragile than his.

If in doubt, partial drain, refill and SLAM to see how things look. AT least you'll still have the pool ready ... which won't be too long now before we hop in. Good luck!

 

[JoyfulNoise]

Has it rained recently there? Do you know how high your water table is? When you remove all that water weight, your pool can very easily float if the water table is high. Think of a cup in your bathtub, filled with water, it easily sinks into the water in the tub. But when you remove the water from the cup, it takes a lot more force to keep it in the water and not floating on the surface. Your ground might appear dry, but when you dig a few feet down, you can easily hit water and start seeing your 4 or 5 foot hole filling with eater at the bottom. I don't know the extent of damage floating a plaster pool would cause, but I imagine it would be quite extensive.

- - - Updated - - -

If you're really set on draining your pool, dig a hole 10 feet away from it that's a foot or 2 deeper than the pool and see how far down you get before you start hitting water.

Austin Texas has one entry in the USGS database for groundwater depth and that survey well (somewhere around W Stassney Lane and S. 1st Street) puts the water table at roughly 166ft below the surface. So his pool is not likely in danger of floating unless there happens to be ground water higher up near his surface. Anyway, digging a 10ft deep hole requires more than a shovel...

To the OP,

I think the main point is this - draining the pool is almost never really necessary but, if you do decide to drain it, you've got to complete whatever work you plan on doing to it quickly or else you risk compromising your plaster. As you've said, the pool is 30 years old and you've only owned the home 8 years. So, if the plaster was never redone in that pool, you have some very old plaster that will likely crumble if you hit it with too powerful a spray from a pressure washer. Your best bet is to rehab the water as much as possible and then save up for a remodel job where you can get the plaster and any tile or coping work done in one shot.

Good luck to you. Let us know how it goes.

 

[Technigogo]

Pat, thank you for looking at my situation for me. Since we are geographically close to each other, I place high value on your take.

Matt, thank you for looking into the USGS data, I was searching for that too but had not found it yet. You are very right on digging a 10 ft hole in Central Texas west of IH35, you will need a backhoe to do that. I am 52 and lived here all my life and I don't think I have *ever* successfully dug a hole deeper than 2 1/2 feet deep and that was with hammer-drills, sledgehammer and long, heavy pokey rod and about 4 hours of work. You are right on about the plaster, the reason for the delay is that our neighborhood is being forcibly annexed by Austin and we have a long list of things to get done that require permitting or won't be allowed after the take-over in 2020. Such as 10 foot privacy fences, a pool house/cabana, 1800 square foot of concrete for decking and other out buildings. That will take all the money I care to spend over the next two years. The plaster will have to wait till 2021.

Thank you to all the advice above. What I plan to do is just hold off on the draining until Friday morning. Then I will have the latter part of Friday and all day Saturday to work. I will *test* a small bit of area with power-washer on a wide-disperse nozzle. If the chips start flying, I'll stop andl just fix my spa light that is out and refill the pool.

 

[lightmaster]

Wow, the water tables 166 ft down in Texas? In my yard, if I dig 2 feet deep I start seeing damp soil. I wasn't expecting him to actually dig that deep, just figured he might see water before then and know if there'd be an issue. Just didn't want him to start draining and find his pool was starting to float.

As a side note, I imagine it's a real pain to dig a well there. My shallow well is only around 40-50 feet deep and gets enough water to fill my little pool without noticing any issues.

 

[borjis]

Even at that (presumed low water table) I would still open the hydrostatic valve if you do drain.
(found under the main drain cover) "IF" there is water it will come up through that instead
of damaging your pool and plumbing.

No way I would take a chance having it empty without the valve open.

 

[Technigogo]

Even at that (presumed low water table) I would still open the hydrostatic valve if you do drain.
(found under the main drain cover) "IF" there is water it will come up through that instead
of damaging your pool and plumbing.

No way I would take a chance having it empty without the valve open.

Are you certain that all pools have that valve?

My pool was built in 1983.

 

[triptyx]

Not all pools have a hydrostatic valve. They're unheard of in places with a low water table, and to the best of my knowledge they wouldn't generally be located up on a step - they're found on the bottom of the pool.

 

[borjis]

Are you certain that all pools have that valve?

My pool was built in 1983.

No but a lot of them do.
My pool was built in 1972.

The water table is quite low here, but they did install one during construction way back.

 

[PoolguyinCT]

Not all pools have a hydrostatic valve. They're unheard of in places with a low water table, and to the best of my knowledge they wouldn't generally be located up on a step - they're found on the bottom of the pool.

I’ve been in high water tables without hydro valves & low water tables equipped with hydros...

If you just have mud rings and covers, it is unlikely there is a hydro.. if you have MD dumps, you are likely to have hydro relief valves...

I drill holes in the shell as water level drops.

 

[Technigogo]

Has anyone here ever done an acid wash?

 

[JoyfulNoise]

Has anyone here ever done an acid wash?

Perhaps our folks who are “in the industry” might have. It’s not an easy process to execute and it can easily lead to over etching and streaking if not done right.

You might consider doing a no drain acid wash, also known as a zero-alkalinity treatment, instead. It’s far easier to control and recover from chemically.

 

[PoolguyinCT]

I’ll take the bait.. Give a “no drain wash” a shot, and if you are not pleased consult a pro for an acid wash or resurfacing.

A traditional acid wash is best left to those with experience for a host of safety, collateral and environmental liabilities.

Some have expressed a dangerously nonchalant attitude toward chemical handling, the stakes are high. Experience, training & PPE gear is a must.

I have seen it all from ambulances, irreparable damage & environmental agencies at acid wash jobs..

Acid washes are profitable work, but I consider them blood money.