Flow calculation help for 75 gallon w 20 gal sump

[taulgrl]

I've researched like crazy and still not understanding how much flow I need for my 75 gal tank with a 20 gal sump. I have a Syncra 5.0 return pump (1321 GPH) and need to buy powerheads. I'd like to get two - one for each side of my 4' wide tank. Just starting my setup and plan to keep soft and LPS coral. Not really thinking I'll get into SPS.

I've read that 30x is a good goal (so 30 x 95 = 2,850??) but does the return pump count toward that total flow of 2,850? If yes, that would leave 1,529 for powerheads. Do I then divide 1529 by 2 so each powerhead would be 765ish GPH...?

Ugh! Thanks for your help!
Betsy

 

[00W]

There's a lot of information on this and, to be honest, most of it can get a bit confusing.
There are a lot of other opinions on this and the following is what works for me:

So 30X is fine for this setup so it is said but only base that on the 75 display. So 30x75. 2250.
I count the return. Your's is a lot for that tank. So return it at the surface in two different spots. Great surface agitation that way.
My tank: 75 with 22 gallon sump.
692 return. One outlet at the surface.
2 jabeo ow 20. Back glass angled to front. These are great because they are adjustable.
Plenty of flow. Plenty. Good excercise for my fish. I have no sand. If I did it would be everywhere.
I have some softies flowing in the breeze.
There are way too many things to buy.
Too many choices.
You've done your research so you understand the different kinds of flow so I won't get into laminar flow blah blah etc. You know not to point it right at a coral and that's enough of that.
Flow is more of knowing where to place it and experimentation in my opinion.
The DC pumps are so cool for that.
You don't want any dead spots but there will be some no matter how hard you try. Some are better at it than others. I have a dead spot on purpose. Being bare bottom I use that spot to funnel crap to and siphon it out twice a week.
This works for me but like I said, every tank is different and trial and error with flow takes a while. Play around with it and have fun. Experiment. As your tank grows you may find you need to change it up along the way.
Hope this helps.
Joel

 

[taulgrl]

There's a lot of information on this and, to be honest, most of it can get a bit confusing.
There are a lot of other opinions on this and the following is what works for me:

So 30X is fine for this setup so it is said but only base that on the 75 display. So 30x75. 2250.
I count the return. Your's is a lot for that tank. So return it at the surface in two different spots. Great surface agitation that way.
My tank: 75 with 22 gallon sump.
692 return. One outlet at the surface.
2 jabeo ow 20. Back glass angled to front. These are great because they are adjustable.
Plenty of flow. Plenty. Good excercise for my fish. I have no sand. If I did it would be everywhere.
I have some softies flowing in the breeze.
There are way too many things to buy.
Too many choices.
You've done your research so you understand the different kinds of flow so I won't get into laminar flow blah blah etc. You know not to point it right at a coral and that's enough of that.
Flow is more of knowing where to place it and experimentation in my opinion.
The DC pumps are so cool for that.
You don't want any dead spots but there will be some no matter how hard you try. Some are better at it than others. I have a dead spot on purpose. Being bare bottom I use that spot to funnel crap to and siphon it out twice a week.
This works for me but like I said, every tank is different and trial and error with flow takes a while. Play around with it and have fun. Experiment. As your tank grows you may find you need to change it up along the way.
Hope this helps.
Joel

This is so so helpful Joel, thanks for your quick reply! I realized shortly after buying my return pump that it was too much but I hadn't considered creating two surface returns. Great idea! You are so right that there are way too many things to buy and too many choices. I can't wait to get past the equipment / plumbing phase and get some critters into the tank!

 

[KStatefan]

I have a Syncra 5.0 return pump (1321 GPH) .



Ugh! Thanks for your help!
Betsy

That is the rating for the pump at zero head pressure. It will not flow that much when installed. You can install a valve to reduce it to what you want also.

 

[Billdogg]

FWIW - I don't include the return pump when figuring out in-tank flow. It's just sort of a bonus IMO.

Although nobody likes to look at them, more PH's with a lower flow rating will provide a more random pattern and help to prevent dead spots way better than just a pair can because you can place them in different places and point them where you need to.

In my SPS dominant 120DT, I use a total of 6 in-tank water movers. A pair of Gyre 250's on the back glass on either side of a center overflow about 1/3 of the way down from the top, a pair of koralia 1500gph on the back glass in either corner, once again about 1/3 of the way down, pointed up and towards the center, and then because flow behind the rockwork is always an issue, a pair of koralia 850's on the sides near the bottom/back of the tank positioned to blow behind the rocks. I don't have detritus buildup anywhere in the tank. At max flow (both of the gyres and the 1500's are on controllers) I would guess that flow is somewhere around 70x+. If they are all off at the same time (rarely, but it happens) the only flow is from the 850's behind the rocks.

 

[taulgrl]

That is the rating for the pump at zero head pressure. It will not flow that much when installed. You can install a valve to reduce it to what you want also.

Thanks! I remember seeing/reading that early on which probably is one of the reasons why I initially went big. Sounds like the best approach is to make a best guess on flow and then adjust as needed!

 

[taulgrl]

FWIW - I don't include the return pump when figuring out in-tank flow. It's just sort of a bonus IMO.

Although nobody likes to look at them, more PH's with a lower flow rating will provide a more random pattern and help to prevent dead spots way better than just a pair can because you can place them in different places and point them where you need to.

In my SPS dominant 120DT, I use a total of 6 in-tank water movers. A pair of Gyre 250's on the back glass on either side of a center overflow about 1/3 of the way down from the top, a pair of koralia 1500gph on the back glass in either corner, once again about 1/3 of the way down, pointed up and towards the center, and then because flow behind the rockwork is always an issue, a pair of koralia 850's on the sides near the bottom/back of the tank positioned to blow behind the rocks. I don't have detritus buildup anywhere in the tank. At max flow (both of the gyres and the 1500's are on controllers) I would guess that flow is somewhere around 70x+. If they are all off at the same time (rarely, but it happens) the only flow is from the 850's behind the rocks.

Thanks Billdogg! I'm starting to see that this is more of an art than a science. I think I'm going to start with some smaller PH's and then add/adjust as needed along the line.

 

[tamanning]

A lot of sump to tank turn over depends on your sump and how you are going to set it up. I've heard people say they like a slower turnover because their sumo all refugium while others are using filter socks or floss or the like . standard flow estimates are not applicable to all setups. I'm using a Eshopps channel design and I'm running at about 650 ghp

 

[taulgrl]

A lot of sump to tank turn over depends on your sump and how you are going to set it up. I've heard people say they like a slower turnover because their sumo all refugium while others are using filter socks or floss or the like . standard flow estimates are not applicable to all setups. I'm using a Eshopps channel design and I'm running at about 650 g

 

[taulgrl]

Thanks tamanning! Good to know that this also weighs into flow. I have a pretty simple sump right now - 1 sock and room for a skimmer and fuge which I plan to setup later. I hadn't seen the Eshopps channel design. Very cool and makes sense for optimizing the fuge.

 

[tamanning]

Thanks tamanning! Good to know that this also weighs into flow. I have a pretty simple sump right now - 1 sock and room for a skimmer and fuge which I plan to setup later. I hadn't seen the Eshopps channel design. Very cool and makes sense for optimizing the fuge.

you're welcome glad to be helpful.