Small leak, rubber spray

[petemay]

I have a very old in-ground cement hot tub (approx. 500 gallons). I lose about a half inch of water or between 6 and 8 gallons a day. I've had the pipes pressure tested and everything was perfect. A leak detection company finally identified a web of tiny cracks in one area of the seating surface as the source of the leak. They suggested having the cracked cement ground out then refilled and resurfaced. I called the pool company that's maintained my pool and spa for 30 years. Unfortunately, spring is here and they're tied up opening and repairing pools and can't fit me in until July. I'm thinking of taking temporary action and using Flex-seal, a rubber spray well-known by anyone who watches late night TV (boat with screen door bottom). Anyway, my only concern is that the chlorine I use in the spa might attack the spray and create an additional problem (like gunk in the pipes or filter or some sort of sticky mess on the seating surface). Does anyone have any experience using Flex-seal or does anyone know of a product that might be used in its stead? Or maybe it's best to keep filling the spa and just be patient. Any advice?
TIA,
Pete

 

[duraleigh]

I'm pretty surprised that tiny cracks are causing a leak that size. ('m assuming a width of 1/16th or less.)

I would be VERY tempted to simply get a tube of polyurethane caulk and, with a small putty knife, seal up the cracks and observe the results.

Poly is quite resistant and there will not be enough of it to matter as far as your tub chemistry.

I wouldn't be stunned if your leak is elsewhere.

 

[petemay]

Yes, actually way less than 1/16th, not even 1/64th. The guy who came over used a needle filled with some red dye to show me the water movement but it didn't seem like much. I just don't know where else to look. The company that did the leak detection is supposed to be the best around. It literally took me a year to get them in here. They kept saying that for the amount of water I was losing, it was unlikely they'd be able to find the problem. Like I said, they pressure tested the pipes and said they're remarkably tight. At one point we thought it might be the hydrostatic valve in the bottom of the spa but, I really can't find one. I think I'll take your advice and try some poly. I've been graphing my water loss. I'll know if the caulk slows or eliminates the leak pretty quickly.
By the way, thanks very much for your input!
Pete

 

[duraleigh]

We would all be interested in the outcome. Cracks that tiny may well be the cause but my "logic meter" sorta' rings an alarm.

The caulk will be a quick, cheap and hardly noticeable fix.......maybe a long fix if that is indeed the problem.