[NickEeriest]

Hi,

After a 10 year break, I'm looking to start a new Mbuna tank. A lot has changed in the aquarium world during my hiatus, but some things have stayed exactly the same. Anyway...

My LFS is trying to sell me an Eheim canister filter for my new tank (probably a Classic 2215). They plan to drill two bulkheads in back for the intake/output connections. In addition to the Eheim, I'd like to put a HOB filter on the back of the tank as well. Now for my question...

I've noticed a lot of reef tanks have an overflow, but I don't think I've ever seen one on a freshwater tank (LFS is not including an overflow for my tank). Are the overflows used exclusively in reef tanks due to the potential for flooding during a power outage? I live on the 3rd floor of my building and a potential tank overflow is a big concern for me. If my power goes out, is there enough water in the canister that I could potentially overflow the tank? The canister doesn't look that big. According to Eheim's website, the Classic 2215 only has a volume of 1.25 gallons. Are overflows only a concern when using a sump filtration system in a reef tank?

I hope this post makes sense. I haven't decided on the exact dimensions of my tank yet, but I'm liking the 50-65 gallon "wide" setups.

 

[NickEeriest]

After reading a few other posts, I think I misunderstood the flooding potential. It sounds like it's not the tank itself that could overflow, but the sump tank (duh!). :lol: So I guess I just need confirmation on the canister. If I'm using a canister and a HOB filter, there is no potential for flooding in the event of a power outage. Correct?

 

[Guams]

Yep, you are correct. It's the sump that would overflow (due to back flow from the display tank into the sump).

Overflows are also used quite a bit in freshwater set ups. It's not a reef specific thing. I have a 40 gallon long that I drilled and put an internal overflow on so that I could run it with a sump. IMO, it's one of the best types of filtration, and the pros of a sump vastly outweigh the cons.[/quote]

 

[RRasco]

You figured it out. HOBs and canisters will not overflow (not under normal circumstances anyways). The flooding potential comes with the sump and in that case, it's not really the overflow that will overflow, but the return line from the sump that can create a back-flow siphon and drain your main tank's water into the sump, eventually leading to water on the floor.

As far as sumps in sw versus fw, I think more sw tanks use them b/c of the additional equipment most reef tanks run. For example, protein skimmers, uv sterilizers, etc. They use the sump to hide all this equipment. Most fw tanks usually only use the sump for bio/mech/chem filtration. Other than that, I think sumps are actually pretty common with fw tanks now-a-days. At least around here. You just have to deal with the noise or figure out how to quiet your system.