Eheim as mechanical only

[phoenix]

I'm in the planning stages of a 125 gallon tank and will probably be going with something similar to RTR's method of separate mechanical and biofiltration. The tank will be high tech planted and I don't want the co2 gassing off. Thus I'm thinking of a 2026 (with a prefilter) filled with ehfimech for the biofilter, and another 2026 for the mechanical filtration.

My question is, what kind of media would be most appropriate for the mechanical side of this scheme. I would assume that I can fill the media baskets with foam and give them regular rinsing. Will the rena foam pads work or are they too small? Maybe the blue foam block from Big Al's would work better? Or just fill It with ehfimech and have a finer filter pad on top?

I would really appreciate any advice from someone who is familiar with the products. It's a little difficult to wrap my mind around this because I can't find any dimensions on the media baskets used in the Pro II.

 

[JSchmidt]

I also subscribe to RTR's model for isolating mechanical and biofiltration. I like Eheims and I use them as biofilters in many of my tanks, but I don't think they're the best choice for mech filtration. Although they are quite efficient, they don't have as much flow rate as other filters, and flow rate is pretty important to me in a mech filter. They're also a bit more difficult to open and clean than other types of filters, and I think mech filters should be as easy to maintain as possible, to encourage frequent cleaning.

For mech filtration, I use (in addition to a prefilter sponge on my Eheim biofilters) either a powerful HOB filter (I really like prefiltered HOT Magnums) or an internal canister filter. I even have some cheapo AquaTech filters from WalMart (made by Marineland) that I pack with AquaClear foam that work well, although if you're worried about blowing off CO2 those might not be as good as a HOT Magnum.

Just my two cents' worth.

Good luck and let us know what you go with.

Jim

 

[RTR]

I don't use many external Eheims for mech-only filtration either, but when I do, I use Eheims sponges which are pre-sized to fit. As they last for years, the initial cost is trivial.

For a planted tank, HOBs are not a very good idea, huge waste of CO2.

 

[phoenix]

Thanks for the input so far.

Does the discharge pipe on a HOT magnum go beneath the water line like it does on Eheim canisters? It appears that way from the picture but as you can tell I've never used one. If it does then it may also be a candidate for consideration since I am worried about wasting co2. Is it really beneficial to use a prefilter on a filter that is mech only, especially if it will be cleaned often? And doesn't the HOT magnum have the same flow rate as the Eheim 2026? I guess if they both have sufficient flow rate for a mech filter then the only question is serviceability and price, perhaps along with reliability.

 

[JSchmidt]

The discharge of a HOT Mag can be totally below the water surface.

The benefit of using a prefilter on a bio-only filter is that you reduce the pollutants that build up in the tank (by exporting crud before it breaks down) and you decrease the frequency with which you need to tear down the canister. Both are good reasons, IMO, to use a prefilter.

My HOT Mag prefilter sponges are much dirtier than my 2028 sponges after the same amount of time. That says to me that the HOT Mag is pulling more flow.

HTH,
Jim

 

[RTR]

The desirability of prefiltering a mechanical filter (whether internal or external) is based on one objective critereron and one subjective one. It may be beneficial to prefilter if the prefilter is coarser than the filters inside the unit, and if the prefilter is frequently rinsed (daily or alternate days rather than weekly). The first is objective, the second highly subjective. If I don't clean my prefilters more frequntly than the unit to which they are attached, they are accomplishing nothing IMHO. If they are sufficiently accessible that I tend them more frequently, then they are of some benefit in getting debris out of the system before it is digested.