System Water Turnover Rate Question

[silver surfer]

I have two tanks tied into one sump. The sump is in the basement. My 120 is upstairs and has a very high turnover rate due to the of the return pump. The other tank is a 300 down in the basement. Due to the elevation of the sump my 300 does not have a super high overturn rate due to the drain lines capacity to drain in the sump. But since then 120 is tied how does the slow return rate in the 300 really matter?

 

[jef4y]

Yes, the slow return rate of the 300 matters.

So for simplicity let's say you have 500G in this system. Ideal turnover is somewhere between 1500 - 5000gph (I lean more towards the lower end). If you turn over 1000gph in the 120 and 500gph in the 300 you have a turnover rate of about 9x/hr in the 120 and less than 2/hr in the 300.

The 300 will suffer in quality as your entire system volume is contributing toward handling the combined bioload of the the system, and is the largest body of water, yet gets the lowest turnover.

Does that make sense?

Overall, I believe at a MINIMUM you're going to want a 3x/hr turnover rate through your overflow. If you can do that in your 300, then whatever your 120 has isn't going to matter much. Just make sure you meet the minimum, but you still need to look at both tanks individually.

 

[silver surfer]

I am running an iwaki 70 on the 300 but have it valved down a little. It's running about 1100 gph.

 

[acroholic]

Silver Surfer;801201 wrote: I am running an iwaki 70 on the 300 but have it valved down a little. It's running about 1100 gph.

1100 gph turnover on a 300 is fine, and nothing I would call slow anyways. Nothing wrong with low flow rates through your sump. Main thing is to have adequate in-tank circulation. You want to avoid too fast a flow through your sump, as things like bubbles from splashing/skimmer return won't even have a chance to clear before they get sent back to the displays.

 

[grouper therapy]

Acroholic;801203 wrote: 1100 gph turnover on a 300 is fine, and nothing I would call slow anyways. Nothing wrong with low flow rates through your sump. Main thing is to have adequate in-tank circulation. You want to avoid too fast a flow through your sump, as things like bubbles from splashing/skimmer return won't even have a chance to clear before they get sent back to the displays.

Agreed! The only time that a slow turn over rate can impact a portion of whole is when the that part is producing more undesirables than the rest of the system can remove.

 

[silver surfer]

Not worried about bubbles, have filter socks and a 75 gallon mrc sump. Internal circulation is currently 3 mp40s and a 4th one will be added in the future.

Just have an Achilles tang and going to add a clown tang and I know the clown tang needs great oxygen levels