WOW! I have not hatched eggs yet, but look forward to it sometime in the future. Have you looked into building a filter for your pond? Lots of info out there.. I'm thinking about trying to locate the pump in the filter box, after the filter media so the pump is basically pumping clean(er) water and pulling water from the pond through the filter... I can't think of any reason why it wouldn't work... yet anyway!
Yup, I sure have and I have a working prototype going after MUCH trial and error. (I say that even as I am preparing for the next iteration). I will first point out that my objective for filtering the pond is not to create a crystal clear Koi pond. My objective is to reduce the number of water changes I have to do in order to conserve water.
My first pump was a cheapie Lowes fountain pump. I bought an overflow strainer to act as a pre-filter that screwed onto the pump input.
The overflow strainer did its job to protect the pump, but it clogged pretty quickly. I added a filter bag which bought me more time but the bag itself eventually clogged, protecting the strainer and the pump but killing the flow. I realized that filtering solid material at the pump level was not going to work (at least for my application) so I abandoned the pre filter concept and went for a dirty water pump that was designed to process solid material and decided to build a filter system that would handle the solid material upstream.
Harbor Freight dirty water wastewater pump
My two stage filter design consists of two 5 gallon buckets, one is a swirl filter and one is a bacteria filter. I may add a third stage clarifier but that's another story.
The swirl filter essentially consists of water coming in from a pvc pipe and "swirling" in a circle which allows the sediment to settle at the bottom of the bucket and the clean water to rise. At the top of the bucket is a drain which flows into the bacteria filter.
Here are some pics of the inside piece of swirly the filter. This whole assembly goes into a 5 gallon bucket.
I am sad to say I don't have any pictures of the bacteria filter, but the concept is simple. I filled a 5 gallon bucket with lava rock which provides great surface area for bacteria to grow. You need to run the input pipe to the bottom of the bucket (unlike my pictures show) so the water is forced to rise through the rocks. You can also buy bacteria balls at an aquarium store, but I like cheap builds.
The filter systems are doing a great job so far, here are some before and after pics:
This is before, the water is duck poop brown. (though you can see the filtered water coming out is clear)
This is about 12 hours later. (It is certainly not drinking water clean, but it is much improved and meets my objective of not requiring a water change)
So now that I had the filters worked out, I had to switch pumps AGAIN. The harbor freight sump pump did a great job, too good in fact as it had several drawbacks for a pond this size. First, at 3800GPH it was able to shoot duck poop soup 10 feet straight up in the air. Second, I had to throttle the flow down (the ball valve in the bottom of the above picture) so it didn't overwhelm the filters and empty the pond through the top of the filters. Third it drew 400 watts, which would have equated to a major electric bill at the end of the month. Finally, the ducks thought it was the funnest game in the world to mess with the float switch and turn the pump off.
So I ordered a low wattage dirty water pump that only draws 40 watts, can handle small solid material, has a flow rate of just under 1000gph and doesn't have a float switch.
The pump has been installed for a couple of days and is running extremely well. I will provide updates as they happen, but I will be on a business trip for the next week.