Flow for FOWLR's


New member
I upgraded my 75g to a 125g. I have 2 koralia 4's along with a 500gph return pump. Would there be any increased benefit of adding 2 more koralia 4's. I do have a few maxijet 1200's that I could use for some spot flow.
I would say as a minimum, 10 times the tank volume per hour, but 20 times is much better.

There are many that say you do not need strong flow in a FOWLR, but I disagree on several fronts:
1. Strong flow means the LR will "work better" as a filter.
2. Strong flow keeps detritus in suspension where it will make its way to the skimmer and get bronken down / drawing out.
3. Good flow will improve oxygen levels and result in better pH etc.
4. Good flow will keep your fish fit and healthy, rather than fat and lazy.

There are other reasons too, but they are the main ones......

Add up the flow rate of your powerheads, and aim for 20 times...... you can get away with 10, but 20 is my recommendation, and 30-40 times is perfect!




Registered Member
My question about FOWLR flow is how do you keep the sand from blowing all over. I agree that the more the better, but if I turn my streams over 40% - sand goes everywhere. And even at 40% the front of my tank is void of sand.


New member
I am also interested in what jmicky41 asked.

Also I have a 90g that recently finished cycling and I added about 80 snails (Different species) 2 days ago as my Clean up crew. I have noticed that the snails produce allot of waste and most of it seems to be setting on the SB. Which doesn;t make me happy as it makes the tank look dirty. I have 1 MJ1200 and 1 MJ900 along with my return which is running from a Mag7. I am assuming I don't have enough flow to lift the waste from the SB.

Should I add more power heads?
What would be the recommendations considering what I already have?
And how would I prevent a Sand storm with more flow? I don't want the Snow Globe effect.
I was thinking of getting 2 Koralia 4's and setting them to the front of the tank and placing the 1200 and 900 to the back. Would this be overkill?

Advice and recommendations please.

Thanks in advance.
Its all about directing the flow - although it is alot easier said than done. Flow that is blowing sand up is mis-directed, and alot of energy is being wasted..... better to direct the flow at the rocks, and let it blow up and over the rockwork. Try postioning them a little lower in the water and angle them slightly upwards (again easier said than done) - tunze's in particular tend to "hang" with a slight downward bias.

Of course you are still going to get sand movement, but its all abotu tweaking it.

You can also use a thin layer of heavier sand, and bits of gravel and rubble etc..... in a FOWLR this coarse layer will also help protect the worms and pods from total decimation from predator fish.

BUT..... having said all this.... it is an uphill battle all the way.