Return Flow Design Q's..

[jlehigh]

I have an issue I am problem solving for so I thought I would solicit feedback from the board..

My 280 obtains most of it's flow by way of an 8way OM wavemaker pushed by a Dolphin Aquasea 4700 with a total of 14 inlets. I also have a mag 12 for a return pump which I guestimate is turning over about 970GPH.

This keeps my tank very stirred up. VERY stirred up.. In fact thats kinda the problem. Detritus is always in my water colum negatively impacting the water clarity. To remove detritus I use wet skimming, and 25 micron filter socks on my drains both of which seem to do a good job catching what gets to them but it appears plenty of the crap is in perpetual motion inside the display.

I have tried re-pointing the inlet's locline nozzles ect ect however the only time my water clears is when I configure a pattern that lets detritus settle, and I dont want that either. I want UP and OUT.

BTW those of you looking for great advice on designing flow look for Mojoreefs flow workshop..

Now to my current quandry: I am thinking of beefing up my return pump for better success and I can take two approaches..

1)Get a preasure rated pump capable of pushing 2 eductors and generate allot of wide flow in the tank while hardly increasing the turnover volume. (Iwaki 70 or equiv Blueline)

OR

2)Get a flow rated pump and simply increase the turnover in the tank significantly. (Ampmaster 2700/3200 or Sequence w/similar rating)

What do y'all think?

 

[reedman]

Go for option 1 John. You don't want to increase the volume going through the sump. Your skimmer is producing skimmate and your filter socks are collecting detritus which means it's getting to the sump, just not enough of it. That would be my choice anyway.

It's like your detritus starts to go toward the overflow and ends up back in the main suspension rather than actually getting into the overflow. I still think option 1 is the way to go. If you move too much water through the sump too fast you won't be able to process it with the skimmer.

my humble 2 cents worth

 

[wrightme43]

or you could maybe make a purposeful dead spot, and then shiphon the junk out.

 

[dnjan]

Reed - I don't understand your response. If he is using filter socks for 100% of his overflow water, then all the water that goes through the sump should be having the visible detritus removed. Therefore, if there is still visible detritus in the tank, he needs to have a higher percentage of tank water (per unit time) going through the sump, where the filter socks will remove the detritus.

The current flow in the tank is keeping the detritus in suspension. That detritus-water smply needs to get to the sump.

 

[bc_slc]

I was going to say the same thing dnjan. I would increase the flow to your sump. The skimmer and filter sock don't have a chance to work on what is in the water column if it doesn't make it to the sump. The skimmer may become less efficient if the water moves through the sump faster, but it will process much more of the water making it more productive. Also, the filter sock's production is based solely on what overflows into the sump. Lastly, if you have baffles then the detritus will collect in the sump.

If you set up educators, you are only going to stir up what is in your water column. That would work great if you couldn't keep debris in suspension, but that clearly is not your problem.

Mat

 

[reedman]

That's certainly one way to look at it. I run filter socks to polish the water. I think they are too prone to forgetting and contributing to Nitrate production. If the thought is to run the filter sock 24/7 then yes, I agree, Higher flow through the sump would get more of the particulate out of the water column.

I was thinking that the particulate isn't making it into the trough. It's in suspension and not getting into the trough to go down the overflow to the socks & skimmer. If you inrcease the flow in the tank to get the detritus into the overflow it will go through the sock & skimmer. Two different schools of thought. Both should get the job done.

 

[jlehigh]

Hence my dilema

Moving 6000gph via eductors will certainly move allot of water around also increasing the chance of matter getting into the overflow.

Increasing the tank turnover by 1000gph will ensure 1000 more gallons per hr gets into the overflow.

I think the eductor method relies again on flow design and positioning more so than the beefing up the return however there are also significant benefits to the flow pattern eductors offer for my corals..

I haven't seen a calculator out there that makes reccomendations on tank/sump turnover.. I guess nothing in reefkeeping is an exact science.

 

[jlehigh]

Here is a Diagram of the Tanks inlets. The long bars represent my spray-bar on the bottom/back of the tank.

 

[jlehigh]

Here is a Better diagram that gives you an idea of how the flow in the tank works.

I am currently running the OM option 3. Each port is fed for about 7 seconds before switching.

 

[dnjan]

If:

1) you already have the detritus in suspension in the water column, and

2) you don't have some magic way to separate the detritus in the moving water so that the water with the higher detritus concentration is the only water that goes through the overflow (some kind of cyclone-separator),

then simply increasing the flow in the tank will not increase the amount of detritus making it to the overflow where it can be removed by the filter sock. If all of your detritus is in suspension, you need to get a higher flow rate through the filter socks.

Remembering, as Reed mentioned, that filter socks 24/7 are an increased maintenance requirement.

 

[jlehigh]

Complete deletion due to mispost...

 

[jlehigh]

Well I might as well add something to make up for the misfire

I added 2 penductors driven by an Iwaki 70RLT and the result was awesome.. The penductors are angled at a 45 degree angle sweeping the tank floor and it pushes detritis into the overflow much more effectively.

Thanks guys!