In ground pool leak

[DirtyRat91]

I'm curious what options/suggestions you guys recommend for my current situation.

The past two winters, I've had a water level problem. During the summer, never had to add water. Even with kids swimming daily, water level was never an issue. However, it started last winter. The water level was stupid low, and I blamed the cheap solid cover I laid on the pool. I use a solid cover, and occasionally drain off the rain water that collects on top with a siphon. I figured the cover had a hole, and I wound up draining the pool water as well. However, this winter I used a new cover, should be hole free, but furthermore, we've had a dry fall. I really haven't drained the cover at all, and yet the water level is dropping dramatically. I just visually checked, and I'd estimate there's 18" of water left in a 4' pool. I do not drop the water level when closing, so it has lost 30" in about 4 months. Or about 7-8" per month. Seeing how the average rainfall in my area is around 4"/mo, this seems like it could become more of an issue this year.

Anyhow, further info, it is a liner pool, the only thing below the 18" line currently is the central drain. (Uniform depth pool, one drain directly in center of roughly 14x32' pool) I'd have to peel back the cover to check, but I suspect even the steps are above the water line now. (Bottom step is a feature of the concrete/liner, plastic steps terminate one above the floor level)

Ignore this until it becomes troublesome during the summer? Or is there a cheap fix while the water level is low?

I know that pool ownership isn't for the 'cheap fix' mindset generally, but I literally just quit my job to start my own business, and until I see respectable income, we're on a 'watertight' budget. Mmmm, poor pun there.

 

[Texas Splash]

Ignore this until it becomes troublesome during the summer? Or is there a cheap fix while the water level is low?

The problem with ignoring the problem now is the extent of water loss and how low it is in your pool. We typically advise owners to not go any lower than about 18" or so to avoid problems with the pool shell shifting, lifting, or walls collapsing. The vinyl could also begin to move which would be another problem.

With water dropping so low and nothing left but the drain, you might consider trying to close-off that drain or perhaps create an airlock to see if that has any impact on the water loss. If possible, try to fill the pool back to a reasonable level (at least 50-70% full) to support the liner and shell. See how that works for you.

 

[DirtyRat91]

Update:

A bit careless I admit, but I totally left the pool to its own devices. My pool closing process was ruined for the 3rd year in a row, despite my best efforts, so I just let it rot. The water level loss has slowed to a crawl, or stopped altogether. It really hasn't dropped much since I posted this last. My pool isn't terribly deep, 4' uniform depth, so the remaining water (18"), which I just measured is still more than 1/3 the capacity of the pool.

I've had an old high school friend, now pool guy, come out and try to check it for a leak. The 18" of water is dark green and has no visibility, so he said there was no good way to test the leak, but based on experience he believes the main drain (likely the plumbing of the drain) has a pinhole leak. In my limited experience and pool knowledge, this makes since to me. My pump runs 24/7 during the swim season so the main drain plumbing has pump suction applied to it, and the water pressure is low. When the pool is winterized, the pump is off obviously, and the weight of 14k gallons of water rests on the drain pipe. Any small crack/hole would slowly drain out the pool until the weight of the water above isn't sufficient to force that crack open wide enough to cause significant water loss.

The solution he has recommended doesn't sit well with me however. He wants to plug off the main drain, permanently. He says on a pool as shallow as mine the skimmer will suffice for circulation. While I have a cutoff valve on both the main drain and the skimmer at the pump, I've never run the pool with the drain shut, only close it during vacuuming. So I'm not sure how the pool would respond only with the skimmer. Also he says he'll have to remove the liner to plug the main drain. It sounds labor intensive to do a patch repair that I don't really want.

I did put a timer on my pump a few years ago when I replaced a dead pump. I did so thinking the 24/7 pump demand shortened the life on the pump. I probably got over aggressive with the off time, but I had algae problems during my timer days. While the FC levels of the pool were always fine even when I'd get algae creeping in, I blamed the lack of circulation allowing parts of the pool (sunny spots) to dropping to very low FC levels, and algae getting a foothold here before the pump would stir up the chlorine again. This is why I'm hesitant to do anything to reduce the circulation in my pool. Over thinking things? Probably. But I'm curious the opinions of you folks.

I've also purchased a SWG which I'm preparing to plumb. Pool friend has since advised that salt is very damaging to pools and I should not take this route. He suggests I try 3" tabs, which I've switched away from years ago and have never been happier.

 

[Texas Splash]

So a few responses to what you mentioned:
- Could the leak be form the MD? - sure. There's also a chance you have a hydrostatic valve in the MD that protects the pool from a high water table. If that goes bad, it can develop a leak as well. So it would be good to inspect that area once you clear the water.
- I will also say however that it's possible the leak is at the side of the liner right about where the new waterline stopped. Or, if you have anything else at that level like a return jet or light fixture, it could be leaking there. But many times the leak is at the height of where the water stopped dropping.
- Can you operate without a MD? - absolutely! MDs have certain conveniences, but are not mandatory. My pool uses one skimmer only and so do hundreds of thousand others. So if the problem is confirmed to be the MD, repairs are questionable, and the best solution is to plug, it will be okay.
- I would avoid any chlorine tabs right now as they increase CYA. Right now you definitely need to clear that water so you can address the leak location and get it fixed. For that, make sure you have a proper test kit (TF-100 or Taylor K-2006C) and follow the SLAM page completely (link below).

Clearing the water will be an essential start to fixing the leak issue, and if you don't have a TF-100 or Taylor K-2006C, you really should make that a priority so you can SLAM properly.

 

[DirtyRat91]

Firstly, thank you so much for your continued support Sir Texas. I really do appreciate all the knowledgeable pool folks on this site.

I've owned a TF-100 for perhaps 5 years now, and am very comfortable in its use and keeping proper water levels. Been bleaching for about as long, and am looking to switch to SWG for the convenience (Read: no more daily dosing).

There are no features or anything at the current (drained) water line. While I can't rule out a liner leak, I haven't noticed any tears in it. The liner is very color faded, so a defect would presumably be a bit more obvious to see.



I thought as I wrote the previous line, and considered, actually the bottom of the stairs is about where the water stopped draining. Perhaps the seam at the stairs is my leaking spot? There's a pre molded plastic stair assembly with a seam around it where the liner joins. Thoughts on proving/ruling out this as the leak? Fill to above the lowest stair and monitor? Again it has been around its current level for about 5 months, and drained to that level fairly rapidly. I suspect that if the stair joint is the leak, that it leaked to that seam, then evaporation has lowered the level to what you see in the photo, or about 2-3" below the seam.

Regarding clearing the water...I'll try to attach more pictures, we'll see how this goes. But the return is a solid 18" above the water level. I figure that running the pump to SLAM the pool would cause such an aeration issue that my PH would be out of control. Perhaps leave one of the two returns plugged, and try to rig a hose from the other to under the current water level.

 

[Texas Splash]

Yes, I see now. The water is bad. Certainly can SLAM, but you would have to fill it up to the skimmer for good circulation and to keep the return jets under the waterline. I don't see a location with your profile name, so I have no idea as to whether you have a high water table or not. If the liner was the culprit and you decided to get a new one, it would have to be drained completely anyways, but done so carefully and with the supervision of a professional who knows your water table and what part of the season might be best to drain. The stairs .. hum... certainly a possibility and would of course also be resealed with a new liner. But you certainly can fill it up, SLAM it, then look for the leak either at the low (current) water level to a couple inches above it, the stairs, or the drain. So you have a couple options, just depends on what works best for you. But we'll be watching, so let us know if you have any other questions.