Can't find leak. HELP!!!

[georam1]

My pool is dropping about 1 inch of water a day. The pool is now below the jets and halfway down the pool light. I have spent hours in the pool with a dropper and some food coloring trying to find the leak. I thought it was the main drain but I took an old piece of liner and covered up the main drain and put somethings heavy on it to seal it. Still leaking. I've checked the light and the steps with the food coloring and still cannot find the leak. I've inspected all the seams of the vinyl liner and still nothing. The liner is only 5 years old but has faded badly. Can a liner just get to a point where it basically just weeps or the water just leaks through it without there being a hole? Yes I've tested the pool with the pump on and off. It leaks both ways. I am going to replace the liner but would really like to know where it's leaking first before I do that. Don't want to put a new liner in and still have a leaky pool. Any suggestions or help would be greatly appreciated!

[Denniswiseman]

If you are losing an inch a day that isn't a weep you are losing over 400 gallons a day
Where is your pump / filter equipment higher or lower than the pool?
If your returns are above the water the leak won't be from them unless your equipment is lower than the pool
I doubt that you sealed the main drain by putting something over it and weighing it down
You may have a faulty hydrostatic relief valve in the main drain, have you tried the food dye around it? Or is it possible to block it with a plug?
I don't have a liner but I doubt that it would become porous without visible signs of damage

[georam1]

Pool pump and filter are above the pool. When I put the piece of liner over the main drain I took the cover off of it and stuffed a piece of liner in the hole then put a piece on top with the weight. I have on multiple occasions tried the food dye with the main drain. Thanks for your reply!

[Denniswiseman]

It seems that you may have to get professional help from a leak finding company

[georam1]

Not many of those around here. I'll keep searching. Thanks!!