Flowrate buffer

[atolylica]

Hi guys,

believe other threads have addressed the issue of the advertised vs actual flowrate of Eheim filter. This post is just to share my experience, and hope it can be of some help to you guys.

The advertised flowrate of the Eheim 2028 is rated at 1050 litres per hour against my tank of roughly 54 litres, minus the substrate and driftwoods. That works out to be 19.5 times turnover of the entire tank. That is quite an overkill as I've read 10-12x turnover should suffice. However, I went ahead with the 2028 considering the following factors:

- The 2028 is 2nd hand, so the motor should have considerably slowed down abit. Not sure how old it is as I didn't ask the seller.
- The canister is packed with 3 full layers of CR and biomedia + a small mesh bag of purigen.
- To be connected with a CO2 external reactor, with 12/16mm in/outlet.
- The 2028 has 16/22mm in/outflow holes, so I had to transform them to a 13mm to fit the reactor inlet, then transform back to 17mm at the outlet.
(Didn't occur to me to get a 16/22 inlet and 12/16 outlet lily pipes)

Expecting flowrate to drop significantly due to the above, I figured that the buffer should somehow bring my overkill flowrate to the more acceptable 10-12x turnover. Wanting to know how accurate I was, I used a simple stopwatch and measuring cup method. My actual flowrate works out to be 403 litres/hour. That was quite a huge drop, at least not what I'd expect. Added a submersible pump rated at 300l/hr, which adds the tank turn over to 700l/hr, which works out to be 13x turnover, which turned out perfect without having my tank with a washing machine effect.

So for those getting a new tank, facing algae issues (due to lack of circulation in this regard), hope the above information helps, and save you some time and money.

[Urban Aquaria]

- The 2028 has 16/22mm in/outflow holes, so I had to transform them to a 13mm to fit the reactor inlet, then transform back to 17mm at the outlet.
(Didn't occur to me to get a 16/22 inlet and 12/16 outlet lily pipes).

Yeah... reducing the pipe diameter from 16/22 to 12/16 anywhere along the outlet line would create a huge drop in flow rate, its basically the same effect as adjusting the double taps on a canister filter to reduce flow.

I've tested reducing pipe diameters in canister filters before and found that the flow can drop down 40%-50% lower too. I guess if you can change your pipe back to 16/22, you'll see the flow rate increase back up dramatically.

I remember seeing an ISTA inline reactor that uses a ceramic diffuser + spiral rotor design and it uses 16/22 ports, that could be someting interesting to try with your canister filter.