Pump takes 2 tries to start

I'm having a problem with my pool equipment. The pump attempts to start in the morning as scheduled but is unsuccessful. The pump starts humming and then the circuit breaker flips. If I flip it back on it hums for a second and then starts. There is no air collecting within the pre-pump filter chamber. I tried one morning to bypass my filter and the pump did the same thing. Any ideas? I think my filter canister (which is 15 years old) is worn out and it does have a visible small leak on the side. My thought is that this small hole allows some air to enter the system and I have a small vapor lock every morning. I think it is collecting in the pipe between the filter and the pump and that is why it still didn't work when the filter was bypassed. Sound reasonable?

Anyway, another question: what is a reasonable pump and cartridge filter for a 12,000 gallon pool?

Welcome to the forum!

A humming pump indicates something preventing the pump's shaft from turning.

You might try GENTLY rapping on the motor as it hums (I use the butt end of a hammer). If that works, there's a little corrosion on the contacts of the starter.

If that fails, I'd look under the pump, while it's running to see if there's a drip of water - if there is, the seal assembly is shot and you probably have rusted bearings.

We've talked about this a few times here and a search might help, now that you know the terms to use.

I'll defer to Poconos if it's the first issue (I wouldn't know about it, if not for AL :) ) If it's the seal, I can tell you how to change one, though the pump will be loud and just changing the seal won't fix the damage already done to the motor:(

There are a lot of great folks here that will join with me in assisting you!

Likewise welecome to the forum.

Ted is being too easy. More like smacking the back end with a 2x4. Not hard enough to dent it though.

Check this thread to which I just posted:
http://www.poolforum.com/pf2/showthread.php?t=9444

As Ted said, probably the switch contacts are crummy. The fact that it does start says the starter winding and the capacitor are OK. There are two kinds of hums. The really loud hum says the starter winding is powered and pulling a lot of current. Probably a shorted cap. A lower level hum, which will still trip a breaker, says the starter circuit is open, and in your case, crummy switch contacts. See if this helps and we'll pursue it further if needed.
Al

Thanks for the info. So if I hit the motor and it starts instantly then I need to clean the contacts? Do I hit it while its humming or before it starts or does it matter?

I fire it up. then whack it while it's humming.

So this is interesting. I've been waiting to try hitting the pump but for the last three days the pump has started spontaneously. The only difference is that I set the pump to start a few hours later in the day. However, today I returned home from work to find the pump off. I took the opportunity to beat the living hell out of the pump while it was humming. Unfortunately, the pump kept humming and flipped the circuit breaker off 3 times before finally starting. Any ideas now?

If the 2x4 trick works then it is a very sure indication of crummy contacts. If it doesn't work, really doesn't prove anything. A pretty good giveaway is that it sometimes starts, sometimes not, so it is not a 'hard' failure but a 'soft' failure. The switch contacts are about the only thing that would behave like this. A capacitor can fail either shorted or open and the vast majority of cases is a hard failure. Motor windings usually short or a wire breaks from vibrational fatigue. Another case of a 'hard' failure. Try cleaning the contacts.
Al