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FIlter media order

idris

Member
Joined
3 Jan 2011
Messages
816
Location
Herts
I have two external filters for my tank.
Filter 1 is used as a conventional filter.
Filter 2 has been more of a circulation pump , albeit a slightly under-powered circulation pump.

In the process of a tank revamp, I've added some filter floss to Filter 2 and, when trying connecting a gravel pump, it turns out to be even more underpowered than I thought. I'm guessing the floss, being more restrictive, doesn't help, so it got me thinking about what order the filter media is in.
So I'm thinking bio balls in Basket D and the most open foam in Basket E, then Medium foam in A and B and filter floss in C.

Does that make sense, or would it be better to have the filter media more evenly distributed?

Two filters.jpg
 
Many including myself like to do mechanical filtration first, from coarsest to finest. Finest being filter floss if you use it, some skip it. Then after most of the particles have been stopped you would place biological media like sintered glass etc, and chemical media like purigen.
I dont want particles clogging up my biomedia, which is why I do it in this order. I also use a prefilter on the intake to prevent large stuff getting into the filter.
 
I understand it should be:
  1. Input from tank
  2. Course
  3. Medium
  4. Fine
  5. Bio (if you have any).
  6. Output back to tank.
As far as Filter 2 Maybe: (It would give you more flow and still act a bio filter)
  1. Input from tank
  2. Course
  3. Medium
  4. Output back to tank
I would be tempted to just have course foam in filter 2. You would still get some mechanical and biological. Plus you would get more flow.
Make sure your pipes are as straight and short as possible.

That is my opinion for what it's worth.
 
If you could I would still have something coarse on A that the water will hit first, in my head large particles hitting fine foam will clog up much faster than if the particles were first filtered through some coarser to stop the biggest bits. Can you cut the foam into sheets so you can have more than one kind in a basket? A sharp knife will do the trick
 
Each of the baskets is probably at least 2" deep, so there's plenty of room for two grades per basket.
I've just remembered I've got a tub of carbon gathering dust. Where would that fit in, assuming it's useful?
 
Another tip for cutting the foam: Damp it with water (not too wet) and freeze it for a couple of hours first, keeps its shape much better, especially when trying to cut slices. As mentioned above a very sharp non-serrated knife is the best cutting tool, I favour a Yanagiba. Given the structure of the foam I thought a bread knife might cut it well but practice proved it to be virtually useless. A saw was even worse, total snagfest.
 
Another tip for cutting the foam: Damp it with water (not too wet) and freeze it for a couple of hours first, keeps its shape much better, especially when trying to cut slices. As mentioned above a very sharp non-serrated knife is the best cutting tool, I favour a Yanagiba. Given the structure of the foam I thought a bread knife might cut it well but practice proved it to be virtually useless. A saw was even worse, total snagfest.
There are various ways to cut foam. Whilst I've not tried cutting filter foam, my go-to tool for foam is an electric carving knife. Filter foam has a very open structure (compared to something like upholstery foam) so I guess it might snag, but it's a similar principal to tools designed for cutting foam so should do the business. (And anyone who was around in the 80s can probably find one gathering dust at the back of a cupboard!)
 
The individual strands of a good quality filter foam made from PE (eg Poret) I think have a much higher tensile strength than upholstery foam. Plus the foam is very easy to deform when pressing down. Not sure if an electric carving knife will work well but please let us know how it goes. I found that anything that will snag the fibres was a fail and best results with something sharp enough to cut with almost no downward pressure.

(I managed to cut the 20ppi(?) blue foams in Oase canister into 4 slices with a sharp smooth knife and freezer technique. It is tricky because it is like trying to cut the last inch of a loaf of bread when the crust has already been cut off.)
 
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