So I'm planning my ats for my new skimmer less 90g system. This will be a nutrient rich system eventually full of many filter feeding organisms (fan worms, flame scallops, sponges, etc.) I have an allotted space above my sump to allow me to have a 18.5" x 10" screen lit on both sides in a vertical ats. My issue is that going by recent sizing guidelines (12" per cube/day lit both sides or 24" lit one side) it will be a long time before I may need a screen that big. I thought I could start with one side lit and make 2.5"x10" screens (24"/cube/day) and just add another screen each time my feeding schedule increases. should I have an 18.5" spray bar going with only 2.5" of it being used on a screen at first or make a small spray bar and swap it out for a larger one each upgrade? Also I may need a pump that can be ramped up and down, I'd rather not use a bypass valve as it would be wasting electricity and adding unnecessary heat to use an oversized pump. I recently learned it's actually bad to have an oversized ats so it's thrown me a curve ball in my plans. Any advise or suggestions appreciated.
Generally speaking, you want to size for feeding, and if you want to oversize it, go no more than double what you feed. Also keep in mind that other factors come into play: lighting type, photoperiod, and intensity is a big factor. Type of food can affect the scrubber also. Do you really think you will get to 15 cubes/day of feeding? That's a lot for a 90g. If you are concerned with heat, then the smaller the pump the better. Go with a short slot and tall screen, but the dimensions/ratio is also driven by the light source sometimes. I would just make a new slot pipe for each change, it will likely be 6 months or more between screen size changes if you start with a screen 2x oversized. I'm not sure what you're referring to when you say "bypass valve"? Have you considered tapping off the return pump? Or could use a DC pump to feed the scrubber.
I don't THINK I'll ever be adding 15 cubes a day, but I'm entering the realm of nps and filter feeding organism (many of which ppl can't seem to feed enough) all while going skimerless so I want to be prepared for anything. I'm building an acrylic box for my ats and I don't want to have to build a bigger one in the future. Unfortunately I can't tap into my supply or return lines for various reasons. By bypass valve I mean a valved tee off the pump going back into the sump so you can throttle the pump back without hurting it. What's a dc pump? is there a requirement for screen dimensions (is 2.5" x 10" the same as 5"x5" both being 24" total)?
Yes, for an NPS tank which generally requires continuous feeding, the Algae Scrubber is really the most sensible filtration to you. Anything else would just tend to remove the food, whereas you want to circulate it as long as possible. So in that case, you might be able to go with a larger scrubber, maybe 3x or 4x your estimated cube-equivalent of feeding, and then you can control the algae growth by adjusting the photoperiod and/or intensity. DC = direct current. Google DC aquarium pump. They are flow/speed adjustable, typically they have multiple step settings, some are adjustable via a dial. But $$. All the rage right now in the aquarium world Screen dims don't really make a ton of difference. With a wide but short screen, you have a lot of water flow but a short pass. With a narrow and taller screen, you have less total flow, but a longer pass. So it's all about balancing out what total area you need with the lighting and flow you have available. When you say bypass valve I think control valve. A bypass valve would be what you have on the return pump to tap off of it and control the flow. If I'm reading you right, you are talking about a dedicated scrubber pump, with a valve on the outlet to control the flow. As for the acrylic build, if you want, make the acrylic build as big as you think you will eventually need, and then make the slot/screen as big as you initially need, along with lighting, etc. You may only use 1/4 of the box initially, but if that doesn't bother you, no problem. Also worth mentioning: you could make it full size right off the bat, and then only light the area you care about. You would have a lot of excess wasted flow across the unlit area, but again, if that doesn't bother you...no harm. In this case you would just treat the unlit area as if it didn't exist for purposes of estimating the capacity.
