Leak in my pond liner

I have a new pond liner in an old round galvanized cistern tank (800 gallons). I've only been running my EKO since 12/1/07. The tank was very clean, but I decided for safety sake I would use a liner to make sure it wouldn't leak. I am very confident that the leak is a liner failure and not due to a puncture of any sort. I started getting more and more condensation in the room where I keep the tank and store my wood. Luckily, it is in a separate room in my garage so no damage is being done. My water level dropped and I lost prime because the water level had dropped a foot or so. I still attributed that to evaporation. Especially because I was hauling in snow covered wood, so small puddles are common. Weeks later the water level was lower so I started looking around. Sure enough, my tank (pond liner), had developed a very slow leak. The liner is a Firestone 45 mil EPDM. I called the dealer and I don't think there will be a problem with the replacement, but I'm wondering if this was a fluke or should I look into an alternative liner. I wouldn't live without the storage component of this system and I probably won't deal with the leak until the weather warms. The tank is well insulated, 3" of foam, the voids from the square frame are filled with perlite and the frame is 2 X 6 with fiberglass batts. The top is well insulated as well. I am heating my water to more of a 170-175 degree level which is a change from my first couple of months of burning. Initially, my sensor was giving a deflated read so I could only heat the water to 160-165. I called Dave at Cozy Heat and he instructed me to move the sensor so the digital readout was a true representation of the water temp. It only takes an hour or less to gain that increased water temp on the front side, and it allows me to use the water on the back side (storage water) at least a couple of hours or more. I burn daily for 5-8 hours and I have little to no cycling due to the storage. I have in-floor heat so I really don't need to heat the water to 170, but I really like the extended time I get from the water storage.

Are there any others out there with liner failures? I seems that many people keep their water even hotter than what I do. Is there a better alternative that won't send me to the bank? Thanks, John

I am quite certain that the failure is probably due to one of the creases or folds in the liner. As Leaddog mentioned, there are plenty of them when one takes a square liner and sticks it into a round tank. When I spoke w/ one dealer, he said that the liners are rated t0 about 170 degrees, but he wasn't certain about that. The Ph concept is interesting, I'll look into that. I haven't checked mine yet. Although because it is an open system, I guess it is much more prone to problems in that area. I stopped at Cozy Heat this week and he said he thought it was a little premature to check for water quality problems since the boiler was pretreated by the installer. Thanks for the advise. I am going to look into a pre-fitted liner this time round to see if they are affordable.

I just read on Wikipedia that EPDM is supposed to have a working max temp of 150 degrees centigrade. I wonder how accurate that is?

CORRECTION: There is NO LEAK in my pond liner. I thought I should set the record straight. The crib around my tank seemed to be the source, but with the warmer weather and lack of condensation, it is apparent that there is no leak. I feel bad if a scared anyone away from this storage solution. I believe it is one of the least expensive methods, if not the least expensive method for storing large volumes of water. I also believe water storage is the only way to go. The open system, which was required by the inspector certainly has its downside and condensation is one of them. I thought I had the tank pretty well sealed up, but obviously not. It is something that I'll work on over the summer.

It had been recommended that I use foil faced bubble wrap on the surface of the water. I painstakingly got things pretty tight, but I would not recommend it. It will not hold up. The foil will come off of the bubble wrap and I'm afraid the pieces may get into the plumbing. I removed all of mine, strained out the particles and replaced it will heavy plastic. I'll probably drain the tank this summer and do a thorough cleaning.

I'll put this into a new post since I want the correction to be more wide spread.