Flow rate and need of powerhead?

[Pennyworth]

I'm in the very early stages of preparing for an octo tank (just recently introduced creatures into my tank after cycling and all).

I've read that the flow rate in a reef tank should be at last 10x the water volume.

I've purchased a Reef Octopus space saver 150, rated for 150 gallons and will fit in the small footprint of my sump. It was this or a non space saver 110. The 110 had a higher flow rate in GPH, but was not rated as high.

The space saver 150 is rated at 130gph, so from I understand I shouldn't be exceeding that too much. I figure I can do at least 260, because the return to my pump is divided.

My question is should I get a powerhead to make the flow 10x my tank volume for the octo, or does it require/can it be ok with less?

Am I limited by the sump I chose if the octo needs a much higer flow rate?

 

[Pennyworth]

I meant to include this info: My tank return pump is a Rio 1100, which has a flowrate of 300GPH, so divided going into the sump my skimmer should be able to handle it (if I'm understand that correctly).

So is 300gph sufficient flow for an octopus, or should it be closer to 550gph in a 55 gallon tank?

Would adding a small powerhead to get it up to 550gph affect the skimmer, or would water not flow into the sump any faster?

 

[DWhatley]

I cannot recommend proper flow rate but will say that you should probably not exceed the bulk head rating of ONE bulkhead (or at least not by much). So if each of your returns is rated for 130, I would stay close to that number. Over time your lines will narrow with buildup and will reduce your flow so you want to be sure you never exceed their ability. Additionally, keeping the return to a single flow max will prevent overflow should a snail or other object become lodged in one line (lesson learned with a snail).

 

[Pennyworth]

I only have one return, as while the flow is divided into two sumps they are joined by a small pipe, so all water goes through the one pump.

As long as I'm not going to hurt the octo by having a flowrate that is more like 7x(382 is return pump not 300) than 10x I won't bother increasing it.

 

[DWhatley]

Unless you are feeding your skimmer directly from the return line (some skimmer are designed to do this but most use their own pump. I tried a unit designed this way but went back to a pump fed skimmer with better result), your skimmer and return pump ratings don't directly cause limits. You will want to turn as much water as possible through the skimmer but the feed is continual and eventually most will be skimmed.

I know of no reason to add a power head to the sump. A power head is a stand alone unit and won't increase your return. You will want to add one (or two) to the display but you must be careful with shielding the intake (a curious octopus WILL loose an arm to the impeller if it is not octoproofed). I use Koralias placed inside a media net in stead of the older power heads to prevent injury. The power head will help mix the water and help push debris into the water column so it will exit the display and be filtered.

 

[Pennyworth]

That's what I was curious about, if I should add one to the display or not.

From my current understanding if I add another powerhead, say one rated at 80gph (only $15), that would increase the flow rate of my tank by 800gph, making the skimmer far more inefficient?

If my concerns are misplaced, how powerful a powerhead would you recommend for a 55 gallon?

Will definitely place in a media bag or some enkamat for octo proofing.

 

[Pennyworth]

*rated at 800, not 80.

 

[DWhatley]

A power head in the display will not have any effect on the skimmer in the sump but it will move more debris to the sump area by virtue of disrupting additional water and preventing dead spots to collect garbage. I think you are confusing the movement of the water in the display with the circulation to and from the filter. The return pump will provide water movement (less than if the pump was directly placed in the display so somewhat reduced from its rating) and adding powerheads will increase that movement but only the overflow through the bulkheads and the return from the pump effect your turnover (the water that goes to the filter and is seen by the skimmer).

 

[Pennyworth]

Yeah realized that the last few minutes of further research, thanks dhwatley.

So adding in an 800gph powerhead to the display tank should be fine for the octo once proofed, and perhaps even a second one?

I've been reading octopuses tend to prefer low flows while others saying high flows, so just want to be careful.

 

[DWhatley]

I have found that BOTH are true at different times. Several of mine have used the Koralias to assist shedding their sucker pads. It is not uncommon to see them choosing a den close to higher flow and I suspect that may help with breathing (conjecture only) while at rest. I see them near the Koralias MOST of the time as they approach senescence (one reason I suspect flow may be a breathing aid possibly allowing the gills not to work as hard). You will want to position your powerheads so that they blow into or behind the live rock. This will dampen the impact, help blow debris from behind the rockwork and provide areas of both higher and lower flow.