recommended flow for 75g

Ive got a 75 with softies and a few sps's. I run (2) Koralia 3's and for my return is a mag 9, but mag 7.5 would probably be fine. I have tons of movement in my tank.
 
Here is a easy math
Your flow has to be 20-30 your tank volume for a good circulation

75 x 20= 1500 gph
Thats the less you should have

And the Mag 7.5 does not have a good flow as these pumps loose pressure the more higher you go
You should get a pump that has more head pressure

One thing is movment an other thing is passing more water thru your
sump
 
I also have a 75g tank with (2) Koralia 3's and a mag 9. The mag9 is a little too strong, but I installed a valve to control the flow.
 
Based on my own experience and research setting up a new 75 if it's going to be a good amount of SPS I would go more like 3000-4000gph personally (more in the 40x-50x range). Keep in mind that as the SPS grows in you will probably need more flow so getting something controllable would be ideal I think then you can turn it down in the beginning if you really need to.
 
It won't be 3000-4000 gph through your overflow, the sum of those numbers is just a measurement of total overall water movement. All that will overflow is what's pumped from the sump. How big is your drain hole and what is the gph of the Mag 7.5? That might be a little too much.
 
To add to the above,

You will want the vast majority of the flow coming from powerheads and/or a closed loop, and not from your return pump.

For my 75 (( with a 30 sump )) my return is about 500 (( headloss and throttled back )). The rest of the flow comes from 2 SureFlows (( modded MaxiJets )) and a SIEO 1100.
 
ok.. the mag 7.5 is 750g per hour.. i dont know what the flow is with headloss.. but ive got (2) hydor koralias (3,4) which move the water pretty well
 
I am about to purchase a return pump for my 75 and am also debating flow. I like the Eheim 1262 Hobby Pump. Seems like they run cooler than the Mag Drives. They are more expensive.

The pump is rated at 900 gph. With head pressure and piping turns can I assume somewhere around 700 gph? Would this be sufficient?

I know it is better to go bigger but to what point? I hear of people throttling pumps back..do these pumps have actual switches to slow them down or is this done by valving the piping?

I only want to buy one return pump so I want to get it right. It will be submersible. Should I go bigger than the Eheim 1262? (900 gph)? If so, suggestions?

Thanks
 
What type of overflow do you have? HOB or is the tank Reef Ready? Most single tube overflows (( RR or HOB )) are going to be rated for 600 GPH -- at most.

What size sump are you using?

Personally for a 75 (( and assuming an averaged sized sump )) I wouldn't want to go any higher then 500 GPH --- you can always throttle back the pump with a ball valve --- after the pump, not before.
 
Hi Todd..Thanks for the response.

I am getting an overflow installed when I have the holes drilled. It will run about 18" across the top of my tank. The guy said it could handle 2000+ gph.

My sump will be a 35 gallon. Why would you not want to go higher than 500 gph? I am thinking the Eheim 1262 will give me somewhere around 700 gph or so. I would rather have too much than not enough.

When you valve back a pump is it not harder on it? Does it run hotter?
 
Sure thing.

With that sized sump (( I have a 30 on my 75 )), you may run into microbubble issues if you are running high flow through it. Plus, with that much turn over you won't get the most out of your skimmer and fuge (( if you are using one )).

With the overflow you are using, the 1262 should be fine, and if you run into issues you can throttle it back with the ball valve. (( I would put one on anyways, --- a true union one --- it make taking the pump off line to clean a heck of a lot easier.

I can't recall all the physics behind it, but a throttle pump will actually run more efficiently if it is throttle back. I haven't noticed mine (( Velocity T2 )) running any hotter, and that pump is 7+ years old, so it doesn't seem to shorten the life at all.
 
The good thing with an oversized pump is that it can be throttled back I guess. I planned on having the return line split and feed the fuge that way with my return zone sitting in the centre of my sump.I will have full control of flow through the fuge this way.

I wasn't planning on splitting my return up to the tank to have more than one place to return the water. I figure the powerheads will be enough flow in the tank. Is splitting a return worth all the extra piping and hassle?
 
I hate plumbing, so I wouldn't do it. ;)

On my 58 I sort of have a split return, but not really. Right where the return gets to the tank I used a Y piece of Loc-Line, but not sure if that counts.
 
Lower flow through the sump yields more efficiency from the fuge and skimmer. I have an Eheim 1262 feeding dual 1" overflows, and the 900 gph is a little too much for my 125g tank / 40g sump. Still, I'm too lazy to throttle it back so I live with it -- still works great just occassionally get bubbles and my chaeto ball could be a little healthier with slower flow. It's an awesome pump, best you can buy for my money.
 
I am tagging along on this thread, I hope no one minds, because I am also in the process of starting up a 75 gallon reef tank.

I am looking at the eheim 1260 (600gph) or Mag7, because I believe I have read that the refugium turnover should be much lower than the DT turnover. Shouldn't the majority of the tank flow come from powerheads or closed loop and the sump/refugium turnover rate be based on what is best for skimming and exportation of negative substances?

In fact, I was actually thinking that those might be a little to strong. I want to say that I read somewhere in a post that the sump/refugium turnover should be 3-5 times the sump/refugium volume. Please correct me if I am wrong.

Thanks
 
i just started a 75 and i put a quiet ones pump on it, the 3300 i think it is, after head loss i am pushing about 600 gph, my overflow has a 1" hole, i am getting a lot of air coming through so i am sure that it is too much for it, going to put my smaller quiet ones back on i think.
 
I guess it all depends on the overflow box and holes?? You hear people saying that 500-1000 gph is too much. Then you hear people running at 4000 gph?

I am going to try the Bean Animal set up with 3 drains and an 18" long overflow box. Seems as though this set up would easily handle around 700 gph after head loss.

As far as flow through the fuge. My fuge will only be fed from my return line so I can put as much or as little flow through as I like. Does this make sense?
 
For me personally I am not worried about what my drain can handle, I bought my tank from glasscages and the drain hole is almost 3 inches in diameter. But from what I understand you want your sump flow to only be between 5-10 times the total water volume or match the skimmer output. (I misquoted on my last post) Because any faster than that and you are possibly returning unskimmed water to the DT which can facilitate an algae problem.

I read this in the following thread started by capn_hylinur:

http://www.reefcentral.com/forums/showthread.php?s=&threadid=1359857&highlight=flow+in+the+refugium

So while our overflows, drains, and returns may be able to handle a large amount of turnover, it may not be the best place to achieve water movement. According the that thread, DT water movement should be achieved mostly by powerheads and closed loops.

So for me I am going to have about 90 gallons of total water so between 450-900 gph would be fine. I think I am going to shot for the lower end because this water will also run through my refugium.
 
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