Background: the ponds will be out of the floodplain, and there are no ponds above me in the watershed drainage area.
I just want to be able to pump water from the creek without introducing undesirable fish fry into my ponds.
The consensus from the previous thread was your exclusion odds improve as you decrease the mesh size on your intake screen, but that also greatly increases the odds of plugging your intake. (I live 45 minutes from our farm. I would like to have the pump on a timer in July & August, but a plugged intake would kill that plan.)
Question for the forum: Is there some mechanical device I could place just before the pump inlet to puree any fish fry in the supply water?
Surely there are mechanical systems in a variety of industries for conditioning the fluid prior to entering the pumps. I am imagining a situation where the pumps are very particle sensitive so they have some type of grinder prior to the fluid or slurry entering the pump.
I am hoping the Pond Boss crew knows of something a little more sophisticated than Dan Aykroyd's "Super Bass-o-Matic 76"
I figure that if I have electricity at the pump, why not use energy, rather than screens, to exclude undesirable fish fry.
Just spitballing here....What if you had a pump going to the top of a screened tank. I envision a large tank cut in half and screened at the top. Then use a second pump to pump the screened out water. The bigger the tank the bigger the screen the more surface area the better chance to keep it flowing.
I would do something like what Mfitzs70 suggested but with these mods.
I would construct a concrete lined hopper at an elevation above the pond of highest elevation. In the bottom of hopper I lay a grid PVC pipe with 1/4" Perfs. This grid would be connected to an outflow pipe (like 2" or 3" polypipe) and this would drain to the pond of greatest elevation. The grid of perfed pipe would then be covered in tamped peagravel and then a layer of size frac sand. You need an arrangement where the water pumped in does not disturb the sand and move it around(maybe something like large rocks). The hopper should have a drain that allows over pump to be discharged( which, if properly designed, should only happen when you need to clean the filter). The position of the hopper needs to be such that spillover doesn't drain into your pond(s).
I presume that the watershed feeding the ponds wouldn't normally be able to sustain the surface acreage but this doesn't mean that they can't overflow in uncommon rain events. For any pond discharging into water that flow directly to the creek, having some free-board and a siphon that lifts the water at the end (so that it exits in an arc) a concrete splatter structure can be built to spread the water in a spray horizontal to the ground. The structure should be long enough to handle distance traveled at maximum freeboard. If the pond spills at the spillway, the siphon isn't adequately designed or maintained. But these should cover you at both ends.
Last edited by jpsdad; 11/25/2010:00 AM.
Common sense is not so common - Voltaire
It isn't what we don't know that gives us trouble, it's what we know that ain't so - Will Rogers
Both of you figured out that it is better to put the screen on the discharge end of the system! I was stuck on the traditional configuration of putting the screen on the intake side - which will be located in a periodically dirty creek.
I think I will first try a 10' slotted pipe wrapped in screen on the discharge end.
If that doesn't work, then I can go to the "hopper" plan at the end of the water supply lines. Let gravity do the work on screening the water.
I think the gravel pack idea would work well in the hoppers. I would add a layer of the permeable geotextile fabric that they use to weep water through retaining walls. Surely fish fry cannot pass through that.
Question for our fish raising experts: What is the correct mesh size for the discharge screen that would be required to eliminate fish fry from the creek?
The creek has LMB, CC, GSF, WCP, carp, gar, and suckers that we have caught or seen. It almost certainly also has BG, bullheads, and flatheads. It also has several different types of minnows. (I have trapped Red Shiners and seen other minnows/shad - that I could not identify without Pond Boss help.)
I don't know who has the smallest fry, but my low-level pond management skills will certainly NOT stand up to unwanted species complicating my projects!
I use the ones that have a ring on the open end, and just duck tape them to the discharge hose on my water pumps. If you remove them after use, they'll last for years.
I always float mine under a sealed 5 gallon bucket, but anything with enough buoyancy would work. I've also used a scrapped 2-3' piece of capped PVC pipe as the float. My thought is that if the outflow was on the bottom, it would disturb the muck on the bottom of the pond, and I don't want that.
The 300 micron mesh is extremely fine, and no fish or aquatic plants will go through it. At most, there will be finely chopped plant parts at the bottom of the bag.
EDIT: I always pull water from the lowest point in a pond, then float the output. It should have been, I pull from the lowest point if I'm just draining a pond. If I'm transferring water from one pond to another, I initially leave both the inlet and the outlet in the pond that's supplying the water, and rake up a 2' circle around the inlet. This disturbs any possible plants or silt, and I pump it until that water clears. Then I just stick the inlet into a 5 gallon pail to protect it from anything that might drift to it, then move the discharge outlet to the receiving pond.
Here's pic of mine. 3" PVC pipe with a 3" to 4" fitting on the end to keep the bag from sliding off when duck tape is used.
Last edited by FireIsHot; 11/25/2003:47 PM. Reason: ADD
Mesh size to capture all fish eggs and fry is 500 micrometers = 0.5mm. That is the standard and fisheries recommended mesh size that we used when I worked for an environmental consulting firm where we routinely sampled / collected fish eggs and fry for various types of projects.
Last edited by Bill Cody; 09/23/2102:40 PM.
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