Water flow rate: help please

[gridley]

My wife and I are setting up our first tank. We have finished the plumbing and are ready to do a test fill with fresh water to check for leaks and to determine the appropriate water level. It has been suggested that I may not have enough water flow . . . so, in the desire to do this right, please advise . . .


My tank is 90G, and the sump, if compleltly full would hold 32G - a more realistic working volume would be closer to 23G (I think). My main drain is 1 1/2", I have a 1" emergancy drain, the return line is 3/4". My pump is a Laguna Max-Flow 600 (600gph). I realize that this is not a standard aquarium pump, but it is what came with the used system. Based on a recommendation I ran the following numbers through the Head Loss Calculator. The laguna pump is not listed on the Head Loss Calculator so I substatuted it with the Eheim 1060 which has a very similar gph rating. The vertical length is 4.25 feet; horizontal length is 1 foot; the pipe diameter is 3/4"; there are 4 90 degree elbows. This works out to 333 gph flow. It was suggested that I replumb the return line to 1". In that case the flow rate increases to 381 gph. However . . . The plumbing at the exit is a 3/4" fitting for the Lok-Line.


In addition I have two Hydor Koralia 2 powerheads at 600 gph and one Hydor Koralia 3 powerhead at 850 gph.

:confused: 1. Do I have enough flow through the sump with the 3/4 line? (approx 33 gph)

:confused: 2. Is there enough benefit to replumb and go with the 1" retrun line and gain approx 50gph of flow through the sump.

:confused: 3. With the restriction to a 3/4" fitting for the Lok-Line, does that in effect create a 3/4" return line?

:confused: 4. With the Hydor Powerheads (2050gph plus the retrun pump) do I have enough total water flow in the tank?


Thanks for the help.

[sponger0]

1. Your system tunrover rate is just below what it should be. But you should be fine there.

2. I think not.

3. That will restrict the flow if the loc line is smaller than the actual return line. Think of it like a road. Only so much traffic go travel on a road based on how many lanes are on the road.

4. Thats is more than enough. Flow rate in the tank should be anywhere between 10x-20x the volume.

[bnumair]

what do u plan on keeping? if its a mixed reef system then:
1 no need more flow. 600gph after head loss is not enough for a mix reef.
2 you can push 2100gph through a 3/4" pipe. ur return pump decided how much water runs through the sump.
3. that will increase head pressure but my guess is not too hard of impact.
4 mix reef is usually 20-40 times the tank so 90*30= 2700 gph.
you already have 1200gph in 2 powerheads. u need aprox. another 1500gph.
you can either increase the size of power heads or get a better pump that after head loss gives u close to 1500gph.

[gridley]

The two of you have been a huge help in thie endevor. I have often been told that there are as many opinions in Reef Keeping as there are people LOL. And based on what the two of you have said, I am understanding that as I begin my system is okay - but minimal. As I proceed - and we want a mixed reef tank - I will need to upgrade the pump and possibly the powerheads. And there is no need to replumb the system.

Any other input is welcome! :fun4:

[fazilosman]

On the return pump, I have read that 4x the system volume after headloss should be sufficient. My take is that you need enough flow (volume and variability) to keep detritus suspended and quickly removed via the overflow.

As an example, my current setup will have a return pump 20x my system volume but also feeding other equiment like N+P reactor. I am a huge advocate for large, slow, random flow in my tank.

Good luck.

[sponger0]

On the return pump, I have read that 4x the system volume after headloss should be sufficient. My take is that you need enough flow (volume and variability) to keep detritus suspended and quickly removed via the overflow.

As an example, my current setup will have a return pump 20x my system volume but also feeding other equiment like N+P reactor. I am a huge advocate for large, slow, random flow in my tank.

Good luck.

But if you have a fuge you dont want everything in it flying around....which would happen with a 20x turnover rate.

[fazilosman]

Agreed, if you have the fuge.

[Palting]

You've gotten excellent advice on the basics of flow rates so far, and you've summarized it perfectly. :thumbsup:

So, on to more arguable points! :D

If and when you go for mixed reef and attempt to get the 20X-40X DT volume flow, my preference is multiple powerheads in the tank. You can direct the flow better with multiple powerheads, so that there is cross currents and chaotic flow. Much better for coral than simple linear "stirring" type of flow.

I disagree on low flow in the fuge. I have a dedicated remote 20 gallon refugium fed with a pump with a calculated flow of 600 gph, That's 30X flow. I have the water coming in from one corner from 3/4" pipes and directed along the longer refugium wall. This creates a large volume of flow without blasting into the tank. The large volume of flow means more water gets processed. There was a discussion several months back, and minds smarter than mine and with more experience, the gurus of the forum, supported the concept of a high turnover rate for the refugium.

[fazilosman]

I took sponger0's point as saying that the flow thru the fuge should not "stir up" any sediments or dislodge macro algae. I had a ecosystem fuge with chaeto and a large flow. The chaeto grew like crazy in that setup. I ensured that the flow simply did not stir up the sediment (miracle mud). Other than that again, the key point is to have all areas in the tank constantly moving with water flow. Slow, random and large volumes is my take. My current system is a 160g DT and I am using 2x Vortech MP40's for internal flow and a WaterBlaster HY-16000 for return.