Recommendations for a SMALL pump

[Bmackkc]

Hello, all.

I have a small (~100 gallon) pond, stocked with a shubunkin (about 8" long), and a total of about 10 smaller (2-3") goldfish.

Generally speaking, the pond is healthy, and the fish are thriving.

Can somebody please recommend a small submersible pump appropriate for this size of pond? I don't have anything fancy; just a spitter to keep the water circulating.

My last two pumps (first was 350 gph; second 250 gph) have failed prematurely; I believe the cause may be due to the fact that either 1) I bought crappy pumps; or 2) I have put undue stress on the pump by clamping down the output hose to reduce the flow to a reasonable level.

Most of what I see in the smaller size is more along the line of fountain pumps, which I don't believe would be a good match for what I need.

Any suggestions would be most helpful.

thanks much.

Mike

 

[DrDave]

Go to Harbor Freight. They have a lot of small pond pumps.

 

[vertigo72]

100 gallon is really small for Koi, even for a single adult Koi. Yours might be 8" now, but it will grow (a lot) and you are going to need some sort of filtration, more than just circulating water, or it will die, literally, in its own sh*t. Just saying because it sounds as if you have no filter at all?

 

[shakaho]

A shubunkin is a goldfish, vertigo. But the pond is still overstocked. I have eight goldfish in a 100 gallon pond, have a pretty good filter, and it isn't nearly big enough. I've had my fish less than a year, and they've grown from less than an inch in body length to an average of 5-6 inches.

What are you doing for filtration?

 

[Bmackkc]

That was going to be my next question once I get water circulating again...What do I need for filtration? I've had a large variety of water plants including water lilies, parrot feather, water hyacinth, etc. Except for right now, my water has been pretty clear.

Again, I'm faced with the size of my pond. The filtration systems I've seen seem to be designed for much larger ponds...500 gal plus. I'm not even sure the filter would fit in the bottom of my pond. Any specific recommendations?

 

[shakaho]

Most of us build our own filters. Go to the DIY section to find lots of descriptions of filters. You can shrink them down to fit in a 20 gallon trash can or a 5 gallon bucket. Mine is in a 9 gallon flowerpot. While it can keep your water clear, the most important function of a filter is to keep your fish alive and healthy. Fish produce a lot of ammonia which is toxic to them. Their survival depends on the actions of nitrifying bacteria some of which convert ammonia to nitrite (also toxic) and others convert nitrite to nitrate, which is not toxic and is used by plants as their nitrogen source.

Nitrifying bacteria are found in soils and grow on any underwater surface. If you had two or three goldfish in your little pond, the bacteria which grow on the surfaces of your pond would oxidize all the ammonia those fish produce and your fish would be fine without any filter. You have too many fish for that, so you need a biofilter. A biofilter is simply a container filled with material with a lot of surface area (biomedia) through which you pump your pond water. Nitrifying bacteria (as well as many other microscopic critters that eat stuff you don't want in your water) will colonize the surfaces of the biomedia. As a result, you will have as many helpful microbes as you would have in a pond several times as big, and can keep more fish healthy.

The simplest biofilter for a little pond is like this. The sponge things beside the box are for simple mechanical filtration to keep large debris from clogging the pump. The little white things in the box are biomedia, where the microbes will grow. You can set a small fountain pump in the biomedia, and attach to it either a fountain tube that will spew the filtered water directly up and back into the pond or you can attach tubing to the pump and use it to send the water to the top of a waterfall that takes the water back to the pond. So the water goes in through the grid on top, through the two sponges into the chamber with the pump and the biomedium then back to the pond through the fountain or the waterfall. The bacteria on the biomedia convert the ammonia in the water into nitrate.

Here's a little 50 gallon stock tank pond with a box filter with a fountain attachment. I made this filter from a file box which was bigger than the commercial filter i showed you before so I could have more biomedia in the box. I drilled holes in the sides to let water in. The sides are lined with mechanical filter material. The pump is this one from Harbor Freight Tools ( that I just spent $25 for before the sale:frown.

The problem with this kind of filter is that small particles go right through or around the mechanical filter pads and get pumped right back into the pond. It makes the water safe for your fish but it doesn't make it much clearer. That's why people use their pumps to move the water to a filter outside of the pond. Those are are the filters described in all those DIY threads.

 

[vertigo72]

Nice post shakaho!

Not wanting to hijack this thread, but do bacteria that convert ammonia in to nitrite have different requirements than those that convert nitrite into nitrate? Like needing more or less oxygen, or sunlight or whatever? just wondering if it makes sense to "specialize" my barrels for either kind.

 

[shakaho]

Well, for a starter, the nitrite-oxidizing bacteria need nitrite to do their job. The nitrite is produced by the ammonia-oxidizing bacteria. Get the idea? :lol:

It's a basic principle of ecology: the more complex the ecosystem the more stable it will be. Ma nature does just fine without her kids trying to micromanage an ecosystem. :nono: