I think we have a leak...maybe at the skimmmer?

[MarkC]

My skimmers have that same semicircular area that yours shows so I don't think that is the problem. Both of my skimmers have it.

[opsman]

Don't panic. If you are pretty sure that the level drops faster with the pump on, you may have a clue. Once the level drops below the skimmer you can rule that part of the system out. If the sanitizer level and ph stays where it needs to be the kids can still use the pool safely. The next thing to consider is the multiport valve on the filter. Quite often the valve that controls the filter will leak internally and send a constant stream of water to your backwash discharge. If this terminates in the yard or into an open drain this is easy to check. Sometimes they are plumbed directly to a sewer and you will have to open the line somewhere to see if water is flowing to the sewer when the pump is on. Once you eliminate this as the source, try plugging the return inlets and valving off the skimmer,vacuum, and main drain. Let that stay plugged overnight and check the results. Cracks in the pipe or separations at joints many times do not leak sufficiently without pressure to show up with the die test. Professional leak detectors will seal off the piping and apply a small amount of pressure, if it holds pressure, no leaks. If you try this method be very carefull as the system was not designed to handle large amounts of pressure and you can easily create a problem that did not previously exist. Keep looking, you will find it.

[opsman]

I just re-read your post and thought of something I found on an old pool once. You said there was no main drain, but there was something that looked like one. Most gunnite pools have an opening in the deep end with a cover. The term main drain refers to a pipe that comes from the deep end goes to the pump. This allows water from the bottom to circulate through the filter. The pool should have one of these. Sometimes the main drain piping will develope a leak and in the interest of economy the owner will plug that off and rely on the skimmers. Additionally gunnite pools many times will have another plug inside the grated enclosure. This plug is the hydraulic relief. Many people think this is a drain plug. It is actually there to be opened when the pool is empty in order to relieve water pressure outside the pool and prevent the pool from floating. I have seen several arrangements where either plug (hydraulic relief or plugged main drain) have been rubber or have rubber components that failed from age. Dive down and look for yourself and see what is there.

[AndieP]

The backwash water flows out of a pvc right at the pump...it is easy to see and there is no water leaking from there.

The water is about an inch below the little arrow on the skimmer (middle of skimmer) that indicates where the level should stay. I was about to convert to BBB from Pristine Blue so there is no chlorine in the water yet.....just minimal residual of Pristine Blue. Should I fill it back up to the skimmer line and get the bleach started and chemicals balanced and then worry with the leak or go ahead and let it drop all the way past the skimmer (another inch) then refill and start on the chemicals.

Sorry to keep asking so many questions....I feel like my head is spinning

[opsman]

probably be good to go ahead and get the chemicals right. you don't want to be in a big hurry.

[AndieP]

I went ahead and filled back up to the skimmer line and started the conversion process.

Ran the pump throughout the night and noted in 10 1/2 hrs we lost 1 3/4 inch of water....compared to 3/4 inch loss is 12 hrs with pump off.

Thanks for the information about the main drain...there is a place down there that looks like a drain but the previous owners keep telling us "there is no main drain" It sounded so weird to me but I'm such a rookie at all this pool stuff that I really haven't explored it anymore. There is no cover over the area but there is a drain cover in the pile of stuff they left over by the pump/filter. We will dive down and check it out as soon as we are done with the conversion process and the chlorine can drop a little.

I was thinking next I need to plug jet and skimmer and turn off pump and measure water loss then...does that sound right? Or do I even need to do this? I guess I should check out the main drain first.

Thanks for your continue help!

[opsman]

Your instincts are correct. Plug those off and see what happens. I think you are probably about to find your problem. Go ahead and explore the missing drain also. Let me know