Bottom Drain Does Not Feed Pump Enough Water And The Filter Loses Pressure

[simonjturner]

Hi One and All

I haven't posted for a while, but I have a new puzzle to solve.

My pump room is above pool level and I seem to have developed a new problem.

When I run the pump fed from the bottom drain only, there is not enough water feed to the pump and hence the pressure in the system drops. Running off the Vac and also the Skimmers works fine.

I first thought I had a hole in the pipe below ground as there was evidence of air in the system, however on further investigation I found the non return valve was blocked. On sorting this problem the air issue went away.

The only thing I can think it may be is either; a blockage in the pipe or the pump I have is not pulling enough. I replaced the pump a few months ago but can't be sure if the problem was introduced at the same time. I do know that last year I ran it off the drain without any issues. The pump is a 3/4 hp and the pool is approx 6 foot deep(1.8 metres).

Any thoughts on this would be appreciated. Thanks.

[MikeH]

Some installations in colder climates have an air valve on the main drain (looks like a bike valve stem) to bleed the main lines when closing the pool for the winter. If you have one check that by puting your finger over it to see if the water flow improves.