Backyard Aquaponics
A place to discuss aquaponics

I have a pondmaster 5000L/h (well 4900 actually) pump running in my trout tank and the screen mesh on the inlet is pretty narrow and does not suck up the trout poop very well so I am constantly having to get the poop out from the bottom of the tank with a small net (the black sponge filter inside the pump screen has been removed).

This is a bit of a pain, but of more importance I'm generally seeing a reading of 1ppm Ammonia on most of my tests (no Nitrites) though. I adjust my ph once per week so its moving between 6.4 and 6.6. Water temp is generally 12-14 degs. I think this ammonia reading may be due to the gunk on the bottom of the tank - I have 24 trout and 15 SP in the system with about 1200L of biofilter and on average feed 400g (3mm floating) per week (1.4g per fish per day) (which I think may need to be increased to get a decent growth rate in the trout once they are around the 300g mark.

I'm thinking about either making up a new pump screen with 5mm holes, or drilling 5mm holes in the existing screen - this should hopefully enable the pump to shift a bit more of the solids and stop the screen clogging quite so much BUT am i courting disaster by doing this from a blocked pump?

Cheers
Matt

Why not just remove the mesh and let the solids go through the pump to the grow beds?

I use a second small pump to circulate the water in my FT, this moves all the solids to the centre where the pump can pick it up. You can do the same by 'T'-ing off your main pump (if there is enough flow) to circulate too. One thing to keep in mind though (and what Ive found) is that trout produce a lot of wastes and muck the water up more so than other species. Cant say its caused amm issues for me in the past though.

Have you thought about using a SLO in the FT and relocating the pump?

-Ryan

That would require a lot of work for Matt to change his system layout so he can incorporate a SLO.

Arbe- After cleaning the screen last night I did not fully screw it back on (only about 4 turns on) and found that overnight it had worked its way loose and a trout had got sucked into the inlet killing the trout and stopping the pump from pumping water So I think a screen is necessary

Ryan - I can't SLO out of the fish tank as it is lower then my GBs - it would take an entire system re config to do that (its a future project!) including a stand for the fish tank. EDIT - beat me to it Arbe

Charlie - Does your system end up with solids collecting on the bottom of the FT, or are they pumped up into the GBs? My solids are collecting around the pump alot of the time so they are in the right place, its just the pump is not moving the bigger bits.

If I move the pump there is some sandy kind of crap under it but thats about it. What size pipe do you have out of your pump? I resized mine a while back from 25mm up to 40mm and the flow increased exponentially.

I'm trying to do some out of the box thinking, I may need some help finishing my thought process. I'm envisioning that you might be able to use some form of a venturi vacuum in conjunction with your pump. I can't find the post I saw earlier today that somebody had an image of such a device. You're basically using a venturi aerator but sucking water up with it's solids instead of air. This may be overthinking the situation a little, but it's a suggestion nonetheless!

AP on my friends!
-Ryan

mines 25mm poly - might be part of the problem - been thinking about running a 25mm to each GB rather than Teeing off - at least that way I will reduce losses - not as much as going to 40mm but it will help...

Your tank sounds pretty clear - I'm taking about 1/2 a cup of gluggy crap out every few days! I'll take a pic...

Bugger.

I have a length of 25mm pipe with 6 to 8mm (can't remember which) holes drilled in it that comes from the pump and goes to the side of the tank. This pipe is connected to the pump inlet. Any stuff that moves around the tank floor is caught by the pipe and sucked up. I monitor where the muck accumulates and block off the holes that don't do much.
This idea came from bunson and there is a picture of his on my system thread.

Wait 'til the trout get bigger and you are throwing a kg or more at them then the crap really starts to fly.

Thanks Marc (& Bunson) - Found the page here:
http://byap.backyardmagazines.com/forum ... f&start=90
I'll knock one up this weekend - has the added bonus of an anti pump dry loop in it as well

Do you have the holes at the 6'o clock position or more like 5 / 7 so that they are not directly in contact with the bottom of the tank - or do the end caps lift the pipe off the bottom enough?

I have holes everywhere and then cover the ones that done work so well for my system. I have some at 6 but most are at 5 and 7. The caps do lift it up off the bottom but that is not a problem as there is still enough suction to get the crap. It sits in line with one of the bottom ribs which also assist in capturing the crap and holding it pending being sucked up!

what sort of pump is it?
- I like the idea of modifying the route of water to pump.

I think you can do it one way or another for most pumps. For mine I have a Hozelock Aquaforce pump so I have water entering the pump through both the cage that surrounds the pump and/or a second inlet where I have attached the long pipe, so i have the best of both options. And its been a great pump so far.