Help with sizing a scrubber for my tank

Welcome Hemant! That's a big tank, so you're going to want a pretty big scrubber, generally.

However with a tank that large, you will undoubtedly have other forms of filtration, correct? Each one of these will take up part of the load.

Scrubbers are generally sized based on the amount you feed on an average daily basis: 12 square inches of screen, lit on both sides, per "cube" of food fed, or the equivalent thereof. A "cube" has been defined to be roughly the size of an Ocean Nutrition cube, or a similar brand of frozen food (about 2.0-2.5 cc's)

So that is the first step: figure out how much you are feeding. There are some conversions that are reasonably accurate, but let's just start with your guesstimate as to how much you feed.

Then, list out what other filtration components you are using, and if you plan to continue to use them (I would, until the scrubber gets mature and you can gauge how much of a "part" it plays, overall)

 

You can probably start out with a 4 or 5 cube/day unit, that won't be too oversized for what you are feeding now. Let it get mature and run for a while, and monitor the water quality until you get a feel for how well it's doing. You will probably find that there is a "set point" where you have the right amount of flow and light that matches up with how much you are feeding.

Then as you start adding fish and feeding more, watch the water quality and adjust your lighting photoperiod and flow to get more algae production. At some point you might hit a level of growth that is about as much as you can get out of the scrubber. Depending on what your light source is, you might be able to continue to increase the intensity and the flow, but a screen sized for 5 cubes/day will eventually get overwhelmed when you are fully stocked. At that point, you can cut a longer slot pipe, or patch in another one on the end of the one you have and add a second screen.

I don't think I would start with a scrubber sized for 10 cubes/day, but you could. Your growth would just be very spread out and you would want to watch the light intensity. Starting oversized runs you the risk of causing photosaturation (too much light compared to nutrients available) so you can go with a lower intensity fixture or split up the photoperiod into several chunks of time. Or you could have 2 lights on each side that you control separately, and only light one section of the screen at a time (or one side at a time).

 

@Hemant I typed a complete response to your post but I must have accidentally closed the window, doh!

The long and short of it is no, I don't make DIY kits because it is a very complex build, one wrong move and you're left with useless parts. I sent a kit ot a known and experienced hobbyist and he agreed it was not for anyone without a reasonable amount of acrylic building experience. The kit is something that I have been asked about many times but at this time I do not offer it. That doesn't mean I will never offer it, but it would have to be something easy to DIY and that is something that I am taking into consideration for the next version, which I am always planning...

 

It was really just a simplicity issue, plus I knew that there was a connection between intensity and effectiveness, and a lower initial intensity seemed to be needed. for the Rev 2, I was using full-current arrays, with diffusers for the start-up phase and individual LED were a pain to wire up (time). The LED board jumpers got rid of the need for a diffuser, and assembly was easily 1/10th the time. I traded my expense for a shorter build time.

I also discovered that bare LEDs at 1/2 current in a tight array (2" on center at 2" from the screen) get you a long way - lots of growth.

You want all 3W Luxeon 660nm Deep Reds. I suppose you could use the Cree DRs but the data shows they are about the same. Philips has always been good for me. Get them from Steve's LEDs and tell them I sent you (Bud) they will get you the right ones.

For the blues, you have a few options. You can use 1W chips, and wire them in series, and then you can run them at 700mA along with the rest of the string. You can run 3W chips and wire them in parallel with each other, within the series string of reds (this is what I did on Rev 2). You can also do the same with the SemiLED hyper-violets (also available at Steve's, they have a 60 degree dome on them that you can cut off 1/2 way up with a thin razor and you get a wider distribution). Or, if you have a dimmable driver and/or controller, you can control the reds and blues separately and never run the blues/violets at more than 50%.

I did look into quite a nice custom controller at one time. Also the MakersLED guys are 30 miles north of me in Ames, IA and I've known them since before there was a Makers...I met them not long after they jumped ship from AI (AquaIllumination, yes, that AI). I considered their controller also, seemed like it was a bit too much, but I'm still considering my options.

I'll go ahead and move this thread over to the DIY section

Bud

 

People have different opinions on this issue. For a while I subscribed to the "scrubber only" train of thought. While you definitely can run just about any size tank using only a scrubber, that doesn't necessarily mean you should. Personally, I run several tanks scrubber-only but these are also relatively simple tanks.

What it really comes down to is redundancy and chemical warfare. There are a lot of thing happening in a closed reef tank that are next to impossible to monitor or predict.

If you choose to have one and only one filtration system, then you have a single point of failure. Here come the what-ifs: What if your scrubber lights fail, and you don't notice for a while? What if you pump fails or you have some kind of blockage that causes growth to diminish or causes part of the screen to die off? There are many scenarios where the single point of failure can lead to disaster.

When it comes to chemical warfare, there are certain things that can get reduced out of a system better using one method versus another, and sometimes one method will not do this task while another will, depending on the form of warfare.

When it comes to our reef systems, we invest a lot of money, time and effort into creating a system that allows the inhabitants to thrive. Using multiple forms of filtration is similar to an insurance policy. You don't always need it, but when you do, you're sure glad you have it. It doesn't always cover all of your losses, but it usually at least takes the edge off. Sometimes, when something goes awry, that's all you need is something to soften the blow, and allow things to recover. In a reef system, this might happen without you even knowing about it.

There are many reasons to use multiple forms of filtration, which is why I stopped towing the "scrubber only" hard-line a while ago.

 

I did 6 reds to 1 blue (or the equivalent). That was per the LED layout. I did 2 blues wired in parallel (half power each). Except now I recommend hyper-violets instead of blues, blues are too intense

 

SemiLED (Steve's LEDs)

 

At least an L4, and likely an L8...there's some time to decide and I'm working on a tool that might help evaluate needs better

 

I will add you to the L8 list!