A few questions for potential new unit

[Leaellynasaura]

I am being gifted a 135 gallon tank from my dad who is upgrading to a larger tank. I will be receiving the tank, the stand and some old tube light enclosures and the lids for the tank. I have been interested in algae scrubbers since I started reading about them as a kid when I had smaller tanks. Back then they were expensive and just to get the catalog mailed to you cost about $25. I want to make this a salt water fish only tank for now and I want to build a water fall style scrubber. Since I currently have no sump or plumbing I would like suggestions on how big the sump needs to be. I plan to use an overflow box since this is not a drilled tank. I am thinking about a sort of pvc horse shoe design.

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I am thinking 9 inch by 9 inch screens. I would have lights on each side of the unit as well as one in between the two screens. To make things simple I would input directly from the overflow box and drain into the sump to be pumped back into the tank. The only other item in the sump would be a heater.

This would give me 162 square inches. Since that is 18 horizontal inches I calculate I need 630 gph. I plan to source a 800 - 1000 gph overflow box and to employ a pump in the 650 gph range.

This will be my first scrubber and first salt water experience. Since none of this stuff is currently even in my house I have plenty of time to get the design right. What suggestions can any of you provide and thanks.

[markstrimaran]

I would go with the biggest sump you can afford or fit, Their are many ways to baffle it to suit your needs. I am still learning about scrubbers, I have a air bubble up, and a waterfall on two 75 gallon tanks.
I am interested in the potential of a scrubber only as a bio filter substitute. I don't know how big , big enouph will be , but I am starting at a 8x18 single sided UFS, in a fresh water African cichlid tank.
I have a baffle that, water gets sucked through, at 600 Gph. Which flows directly to the scrubber.
I think that a option for more lights, as stocking increases is a good idea.

[SantaMonica]

Welcome. Yes that design will work. I'd say it's too big, but you need a minimum size to capture the light from those bulbs, so that's about as small as you can make it.

[Leaellynasaura]

Ok I have modified the design slightly to be more sturdy and I finally bought the parts to build it. My first question is if I have the filter self supporting as in it has legs made of PVC is there any danger to those legs being filled with tank water that experiences very low flow due to it having no where to go? I want the weight of the water to hold it stable.

Edit: I now wonder if simply adding a small hole to each corner of the base will allow a slow flow and thus prevent total stagnation.

My second question is regarding substrate for the tank. I am trying to decide between a shallow or deep sand bed. Will there be no need/benefit of a deep sand bed due to lack of anerobic bacteria in a scrubber tank? I have fallen in love with coral so it will no longer be a fish only tank.

[SantaMonica]

I don't think you will need holes because there will be good flowing in the pipe, even at the closed ends.

I prefer shallow 1 inch sand beds. They look better from the side, are safer, and you can stir them up. And if your scrubber is working, then you will not need the extra nitrate reduction.

[Leaellynasaura]

I finished the unit. I am somewhat concerned the three tabs I left on each grid to lock into place may be counterproductive and block water flow. Note that I originally calculated two 9x9 inch grids, but since I had roughed up the whole thing I left it closer to 10x12.

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[SantaMonica]

They won't block flow, however I think you should put the entire length of screen up in the slot.