Tunze pumps do a great job of moving a lot of water, with little energy and heat, but they have some weaknesses that I have been wanting to improve upon. First they are not fry friendly. Small fish can be sucked in and killed. Second, in a planted tank I find that I must frequently remove small bits of plants from the intakes and from the exhaust grids. I have experimented with two different, but similar solutions to these problems.
Using 1 inch reticulated foam, glued with silicon, I enclosed two Tunze pumps with the top of the enclosure above the waterline. This is a mattenfilter as discussed in the thread called Stream(ish) project (http://forums.loaches.com/viewtopic.php?t=16770&postdays=0&postorder=asc&highlight=matten&start=0
). I obtained my foam from the source that Barsten gave the link to (http://forums.loaches.com/viewtopic.php?t=16770&postdays=0&postorder=asc&highlight=matten&start=0
). It is two inch thick foam, but I found that with a sharp knife I had no trouble slicing it down the middle to get one inch foam.
One pump inside.
With the output grids and the magnetic attachments showing. I cut the holes about 2/3 of the actual size so that they fit tightly.
It's not a very good picture of it installed, but it is the best that I have.
This has been running for several days and seems to be working great. The water level in the open part at the top is virtually the same as the tank water level which means that the pumps are not working much to pull the water through the foam. When I feed, some food gets sucked onto the outside of the foam, but the loaches come around and scour it clean. I think that this will reduce pump maintenance to almost zero.
A second version of the experiment covers a pump directly with one piece of foam and no glue.
Start with a 2 inch thick rectangular piece and a slit in the middle.
Put it on the pump. Make the slot just long enough to fit tightly.
Trim the foam.
In the tank.
I don't really know how much the flow is reduced by the foam. But feeling the current with my hand both before and after, I could not tell the difference. The above two pumps are in my loach tank. I then did the same for my hillstream river tank with a small Tunze pump (6045).
This pump moves about the same amount of water as the three aquaclear 70s that I had in the tank, but uses 7 watts as opposed to 60 watts (for three). The tank temperature in two days has dropped from 79 degrees F to 74 degrees F (from 26C to 23C).
So far I am pleased with how this is working and I think the foam eliminates the problem of having plant debris getting inside the pumps. I should only have to occasionally remove plant debris from the outside of the foam- much easier than removing and dismantling the pumps. The foam also makes these pumps fry friendly.
Which method above is better? I don't know, but I like the simplicity of the second method of directly covering each pump. It is also best for redirecting flow and for ease of removing the pumps for maintenance. I will report back after a few months of testing.