Some questions about flow.

telathas · 08/21/2017, 04:58 PM

I'm wondering if you guys usually add your return pump's GPH when calculating how much flow you have in your tank. Right now I have two fixed speed powerheads in my Nuvo 30L and I'm trying to find a DC powerhead that fits my needs. On my tank I currently have two 528 GPH powerheads (just some cheap powerheads I found on amazon) as well as a Cobalt MJ1200 as my return pump. Assuming the pumps are accurate to their rating, this puts me at roughly 42x turnover which is pretty high.

I guess to make this a little clearer, my questions are:

1. Do you include your return pump GPH into your flow calculations?

2. What is a general rule of thumb for flow for a mixed reef? I've read posts saying 20x GPH for softies, 40x GPH for SPS dominated. Should I be aiming for somewhere around the 30x mark then?

3. Any suggestions on budget controllable powerheads? As much as I'd love to slap a MP10 in my tank, I can't really afford it right now. Am I better off keeping my fixed speed powerheads and saving up for an MP10? I've read good things about Jebaos but I'd love to hear about some of your personal experiences.

4. Something I don't really see talked about much is powerhead placement. What exactly is the best way to position powerheads in a longer tank? I usually see them placed in the back for cube type tanks. Is it better to have them one on each end? What if you only use one powerhead? Front, middle or back of the tank? Back facing front of the tank or vice versa?

mcgyvr · 08/21/2017, 05:05 PM

All totally generic approximations used over the years but..
1) yes
2) 20-30x softies, 30-50 mixed, 50-75+sps not that you can generalize corals needs like that exactly..
3)Jebao PP or SW series.. I use PP8's and they work great and have for a while now.. Jebao seems to be hit and miss with their "1st generation" stuff but usually corrects quite quickly..
4)In general you want to avoid any low flow areas where detritus,etc.. might collect and thats VERY dependent on the specific rock placement,etc.. But I usually recommend at least 2 with one on each side. one blowing across the front and one across the back..

telathas · 08/21/2017, 05:22 PM

If I wanted to get something like the SW-2 which is rated for roughly 660 GPH, would I most likely need to get two or could I get away with one of them along with the return pump? Could I also use one of the fixed pumps with the SW-2 and rely on the SW-2 with providing enough force to vary the flow?

Also, how exactly does the water volume vs the display volume change things? As I said, I have a nuvo 30L so while the water volume is roughly ~30g, the display area itself is only around ~23g. Does that mean I should be using that 23g display volume when calculating my flow?

ca1ore · 08/21/2017, 05:34 PM

No opinion really on rules of thumb; I think they're mostly useless. What you should be aiming for is chaotic glow, and avoid sustained laminar flow. I'm not much of a Jebao fan, though I do use their smaller models on small tanks. Mostly because it gets to be overkill with vortechs on small tanks.

telathas · 08/21/2017, 08:23 PM

So do you guys think I'd be fie with one SW-2 on one end of the tank or is that not enough to adequately provide flow to the other side?

08/21/2017, 04:58 PM	#1
telathas Registered Member Join Date: Feb 2016 Posts: 57	Some questions about flow. I'm wondering if you guys usually add your return pump's GPH when calculating how much flow you have in your tank. Right now I have two fixed speed powerheads in my Nuvo 30L and I'm trying to find a DC powerhead that fits my needs. On my tank I currently have two 528 GPH powerheads (just some cheap powerheads I found on amazon) as well as a Cobalt MJ1200 as my return pump. Assuming the pumps are accurate to their rating, this puts me at roughly 42x turnover which is pretty high. I guess to make this a little clearer, my questions are: 1. Do you include your return pump GPH into your flow calculations? 2. What is a general rule of thumb for flow for a mixed reef? I've read posts saying 20x GPH for softies, 40x GPH for SPS dominated. Should I be aiming for somewhere around the 30x mark then? 3. Any suggestions on budget controllable powerheads? As much as I'd love to slap a MP10 in my tank, I can't really afford it right now. Am I better off keeping my fixed speed powerheads and saving up for an MP10? I've read good things about Jebaos but I'd love to hear about some of your personal experiences. 4. Something I don't really see talked about much is powerhead placement. What exactly is the best way to position powerheads in a longer tank? I usually see them placed in the back for cube type tanks. Is it better to have them one on each end? What if you only use one powerhead? Front, middle or back of the tank? Back facing front of the tank or vice versa?

08/21/2017, 05:05 PM	#2
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	All totally generic approximations used over the years but.. 1) yes 2) 20-30x softies, 30-50 mixed, 50-75+sps not that you can generalize corals needs like that exactly.. 3)Jebao PP or SW series.. I use PP8's and they work great and have for a while now.. Jebao seems to be hit and miss with their "1st generation" stuff but usually corrects quite quickly.. 4)In general you want to avoid any low flow areas where detritus,etc.. might collect and thats VERY dependent on the specific rock placement,etc.. But I usually recommend at least 2 with one on each side. one blowing across the front and one across the back.. __________________ Who me?

08/21/2017, 05:34 PM	#4
ca1ore Grizzled & Cynical Join Date: Apr 2006 Location: Stamford, CT Posts: 17,319	No opinion really on rules of thumb; I think they're mostly useless. What you should be aiming for is chaotic glow, and avoid sustained laminar flow. I'm not much of a Jebao fan, though I do use their smaller models on small tanks. Mostly because it gets to be overkill with vortechs on small tanks. __________________ Simon Got back into the hobby ..... planned to keep it simple ..... yeah, right ..... clearly I need a new plan! Pet peeve: anemones host clowns; clowns do not host anemones! Current Tank Info: 450 Reef; 120 refugium; 60 Frag Tank, 30 Introduction tank; multiple QTs

08/21/2017, 05:22 PM	#3
telathas Registered Member Join Date: Feb 2016 Posts: 57	If I wanted to get something like the SW-2 which is rated for roughly 660 GPH, would I most likely need to get two or could I get away with one of them along with the return pump? Could I also use one of the fixed pumps with the SW-2 and rely on the SW-2 with providing enough force to vary the flow? Also, how exactly does the water volume vs the display volume change things? As I said, I have a nuvo 30L so while the water volume is roughly ~30g, the display area itself is only around ~23g. Does that mean I should be using that 23g display volume when calculating my flow?

08/21/2017, 08:23 PM	#5
telathas Registered Member Join Date: Feb 2016 Posts: 57	So do you guys think I'd be fie with one SW-2 on one end of the tank or is that not enough to adequately provide flow to the other side?