Flow Rate

[MrHermit85]

Hi guys. i bought a 65 reef ready tank, it has a 1" drain and a 3/4 return. I was confused as to what size pump to get? I will be adding a 2nd OVer the top 3/4 return and the sump will be a maximum of 5 feet away. I have never used a "reefready" tank so hopefully someone with a cornerflow can chime in.


Thanks

 

[Josh]

I would use the drilled return as a 2nd drain if it's in the overflow. Run all your return over the back.

400-500 gpm will likely be fine.

 

[MrHermit85]

Cool, that is a great idea. The return is in the overflow. I wonder if I could even make one a full syphon and use the other as a backup? I nearly bought a 1200gph pump that would have been a major overkill if 400 to 500 would do the trick.

 

[Pistol]

Pumps lose flow with head so make sure you are getting the flow you want at the head you have, most pumps drop off pretty quickly with feet of head.

 

[Josh]

Most dc pumps run fairly well dialed down. You could oversize it a bit and you wouldnt see much difference in power costs.

Non dc option would probably be a mag 7

 

[MrHermit85]

Pumps lose flow with head so make sure you are getting the flow you want at the head you have, most pumps drop off pretty quickly with feet of head.

I was going to go with a sicce pro, they supposedly handle head reasonably well but I am sure there will be head loss. According to sicces flowcharts the headloss is pretty high so I guess a 1000gph pump isnt actually that far off from what I need considering their flowcharts dont take fittings into account.

 

[MrHermit85]

Most dc pumps run fairly well dialed down. You could oversize it a bit and you wouldnt see much difference in power costs.

Non dc option would probably be a mag 7

I was considering dc but I was told they dont handle headloss very well and then you are paying a fortune to overate to get the flow you want? Do you use DC and what has your experience been?

 

[Copperkills]

I was going to go with a sicce pro, they supposedly handle head reasonably well but I am sure there will be head loss. According to sicces flowcharts the headloss is pretty high so I guess a 1000gph pump isnt actually that far off from what I need considering their flowcharts dont take fittings into account.

Rule of thumb is 1ft head loss per 90dg fitting...

 

[Copperkills]

I was considering dc but I was told they dont handle headloss very well and then you are paying a fortune to overate to get the flow you want? Do you use DC and what has your experience been?

I’m running a Mag 9.5 currently at 5 ft head and I’ve still had to restrict flow 50%, I’m guessing I’m running my return at 400gph ish. Your sump and your overflow will tell you what flow it wants...rule of thumb was 10x flow through but trend is leaning towards much slower...more processing time in sump...higher flow rate in DT is more important, roughly 100x for SPS.

 

[MrHermit85]

I’m running a Mag 9.5 currently at 5 ft head and I’ve still had to restrict flow 50%, I’m guessing I’m running my return at 400gph ish. Your sump and your overflow will tell you what flow it wants...rule of thumb was 10x flow through but trend is leaning towards much slower...more processing time in sump...higher flow rate in DT is more important, roughly 100x for SPS.

9.5 is rated at 950gph, that is really good flow if dialled back 50% and still getting 400gph. Is it ok to dial back a pump by resyricting its flow?
The mag obviously isnt as loude as people say then as I couldnt hear much noise coming from your tank... How long have you been running it?

 

[Pistol]

it's ok to restrict the outlet, not the inlet, restricting the outlet will reduce the energy consumption as well.

 

[MrHermit85]

it's ok to restrict the outlet, not the inlet, restricting the outlet will reduce the energy consumption as well.

Really? Man you just blew my mind, they didnt teach us that in controls class. Does restricting the flow not strain the pump? I guess the strain would be if the inlet was restricted only as you stated.

 

[MrHermit85]

Does anyone run 2 smaller return pumps for redundancy or am I just going too far now?

 

[MrHermit85]

I know I am straying from topic but is there any benfit to running an external pump other than heat transfer?

 

[Copperkills]

Really? Man you just blew my mind, they didnt teach us that in controls class. Does restricting the flow not strain the pump? I guess the strain would be if the inlet was restricted only as you stated.

Restricting flow just acts as added head height/pressure.

 

[Copperkills]

Sunpoles are not too badly priced though.


9.5 is rated at 950gph, that is really good flow if dialled back 50% and still getting 400gph. Is it ok to dial back a pump by resyricting its flow?
The mag obviously isnt as loude as people say then as I couldnt hear much noise coming from your tank... How long have you been running it?

I’ve had the Mag for a number of years, you can’t kill them. I also have the sump mounted on a neoprene pad, it helps absorbs vibration. I hear it because I know what it sounds like, others unfamiliar with Mag may not know the subtle hum it produces.

 

[Pistol]

I agree with this guy, I have run restricted pumps for many years and some as high as 40 horsepower. On larger pumps the running current is set by restricting the pump, restricting the outlet reduces the current/horsepower of the pump. Restricting the inlet will cause cavitation and destroy the pump.
Ihttp://www.reefcentral.com/forums/showthread.php?t=2635807&highlight=pump

 

[Josh]

There are a few exceptions to this rule but think of pumps this way. More water/air (works for fans too) you are moving the more current (power) you draw. So if you reduce flow it will reduce the power consumption. Opposite of what you would think. They use it as a trick question on HVAC exams.

External pumps generally just handle the head pressure a bit better. I would think you are fine. My sump on my fragtank is about 5 feet away in a closet and i use a mag 5. 65gallon which is pretty close to your tank size.

You went to school for controls? Did you find a controls tech job locally?

 

[MrHermit85]

There are a few exceptions to this rule but think of pumps this way. More water/air (works for fans too) you are moving the more current (power) you draw. So if you reduce flow it will reduce the power consumption. Opposite of what you would think. They use it as a trick question on HVAC exams.

External pumps generally just handle the head pressure a bit better. I would think you are fine. My sump on my fragtank is about 5 feet away in a closet and i use a mag 5. 65gallon which is pretty close to your tank size.

You went to school for controls? Did you find a controls tech job locally?

I am a sparky so there is a bit in our schooling about fluid power and controls but 309a guys dont really apply it unless your with a controlls company.