Aquaponics Pump

[QQQ]

LONG VERSION:
So I set up a very small aquaponics system in my backyard as an experiment. I had a 5-gallon bucket holding 25 goldfish, and a 2-tiered planter with a couple of onions and a few other small vegetables on the top with duckweed growing on the bottom tier. A pump brings water (and fish waste) up from the bottom of the bucket and pours it on the top tier (vegetables) of the planter. The water and fish effluent/nutrients flow through these plants into the bottom tier (duckweed), then flows through the bottom planter and falls back into the bucket with the fish.

I have long-term plans to scale this up to actually produce food using tilapia in a large barrel and a more sizeable hydroponic garden, and to hook it up to a solar panel as a power source.

I'm using a generic fountain pump from home depot (about $25). However, the pump has not been entirely reliable as it stops working every so often and requires me to run some water downhill for a few seconds before continuing its job of pumping water up from the bucket to the planter. It must be running constantly and able to handle fish turds. The goldfish had been doing well but they've started dying off now that the pump has completely ceased to function.

SHORT VERSION/ tl;dr:
Does anyone have suggestions on a pump that will work extremely reliably and with minimal maintenance in an aquaponics system?
I've heard that EHeim pumps are good, so I'm thinking of trying one out, although they're expensive.

[Chaparral]

Gormann Rupp makes good stuff and you can get a good user serviceable model and keep a few rebuild kits handy.

[frigginchi]

If you have a pre-filter the pump will last longer between maintenance.

Something like this will work. You just take the pre-filter out and clean it when you see the flow slow down.

http://www.truaqua.com/internal-filter-ipf305.html

for more info go to : www.aquaponicscommunity.com

[cranemech]

QQQ,
What issues are you having with the pump: does the pump plug up due to solids entering the pump or is your planter too high for the pump to lift the water to that elevation?

If solids are plugging the pump maybe put a screen in the bottom of the bucket. I'm thinking something like a bakers cooling rack to elevate the pump and let the solids settle to the bottom of the bucket. Obviously if the solids need to reach the plants this won't work.

If the pump doesn't have adequate lift then minimize the difference in elevation. I don't know which pump you have but looking at the HD website this pump only has a lift of 30 inches.

And:

[frigginchi]

Btw you have too many goldfish. I'd only put 5 max in it. you will have deaths soon.

[QQQ]

Btw you have too many goldfish. I'd only put 5 max in it. you will have deaths soon.

That's what they said at the pet store. Than I looked, and theirs were way more crowded.
Mine were doing fine until the pump stopped working.

crane: The top of the planter is maybe 12-15 inches higher than the pump. I'm no expert, but I suspect that the pump is straining from constant use and from gunk. I put a screen on the bottom of the input to prevent too much gunk from getting in. However, the gunk ended up building up on the screen and required fairly regular scraping (once every few days).
I'm considering one of those pre-filters. will those still allow the pump to have sufficient suction to clear the water of the crap from the bottom of the bucket?