Run pump while pool not full

[Eddles]

Hi all,

I need the pool ready for this weekend, however I had to drain the pool a few days ago for painting. I'm currently refilling it, and it's only half full at the moment, obviously the water's very cold. The pump has 4 inlets - main drain, pit drain, skimmer & vaccuum. I tried closing the valves for the skimmer, pit drain & vac and leaving only the main drain open and running the pump, but the water doesn't flow, why not? Is it safe to do so, or is it best to wait until the water level goes up to the skimmer inlet?

Many thanks!

[Teapot1]

Do they take the main drain line via the skimmer? Some do, otherwise without being there a bit tricky, system primed, pump pre filter full of water?

[Eddles]

That's a good question - I've not got a clue, to be honest. This pool belongs to my parents. My dad was involved in getting the pool built, but he has dementia now, so he wouldn't know.

I did what you suggested - made sure there's water in the pump filter, and in the skimmer. Started the pump, still no water flow. The water in the skimmer stayed exactly where it was - not even a ripple. When the pool got up where all conceivable ports were underwater except for the skimmer, it still didn't work - lots of air bubbles out of the returns, but that's it. I gave up, waited until the pool was full, and hey presto, it worked like normal. I've not got a clue why this happens - my complete guess is that it's to do with the pool being underground, the pump is just above the water level, so with the water lower than the usual level, there's not enough water to prime the pump? Even if the water level was 5mm under the skimmer inlet, it still didn't work. I don't know, but it doesn't matter really, it works now. So, thank you for your advice, I appreciate it!

[Teapot1]

Ok thank you for coming back, glad its working again. We dont know the height of the pump from the water level as you said a failure to prime. Two thoughts if the water level is quite critical (1/2" of below skimmer) the pump impeller sections can become clogged wich reduces pumping ability and priming, worth having a look at that, can usually be seen via the outlet pipe from the pump.
Could the main drain have been blocked on purpose due to a previous leak?

[Eddles]

Ok thank you for coming back, glad its working again. We dont know the height of the pump from the water level as you said a failure to prime. Two thoughts if the water level is quite critical (1/2" of below skimmer) the pump impeller sections can become clogged wich reduces pumping ability and priming, worth having a look at that, can usually be seen via the outlet pipe from the pump.
Could the main drain have been blocked on purpose due to a previous leak?

Thanks for your reply! The pump is brand new, replaced sometime last year. I think it's slightly above the water line of the pool. No idea about main drain, how do I check? Many thanks!

[Teapot1]

Even brand new pump impellers can clog with particles from trees so worth looking at, I once drove for 3.5 hours to a pool which had a clogged impeller, I previously gave the owner the same info as you but I unclogged it and all was fine, local pool chap just kept trying to sell him a new pump
The main drain obviously come from the base of the pool so 3-4ft lower than the pump but does it connect directly to the pump on its own line or via the skimmer?

[Eddles]

It's an indoor pool, so certainly not any tree particles. The old pump was kaput, it was spinning (very high-pitched whining) but the impeller wasn't spinning, and it was 20 years old, too.

How do I figure that the main drain don't go via the skimmer? Thank you!

[Teapot1]

Best is looking in the skimmer to see how many pipes are connected and how many pipes come to the pump, usual to put the main drain on its own valve so you can isolate it.

[Eddles]

Best is looking in the skimmer to see how many pipes are connected and how many pipes come to the pump, usual to put the main drain on its own valve so you can isolate it.

As far as I can see, there is only one hole in the bottom of the skimmer, and in the pump room, there are 4 pipes coming out of the ground, combining before going into the pump itself. The markings on the 4 pipes are “Main drain”, “Pit drain”, “Skimmer” and “Vacuum”. Each of the 4 pipes have a ball valve.

[Teapot1]

Thats good so you have a separate line to the MD thats the proper way to do it!