New Scrubber for 75 gallon reef

[1cooljeep]

Hello everyone. New posting here. Just wanted to document the addition of my algae scrubber to my 75 gallon reef tank here and see if there are any tips or suggestions that people have as I go along. I've enjoyed stalking the site so far, hope now I have something to actively share.

Some background... I've had this 75 gallon reef tank up and running now for almost 9 months. Things have gone well for the most part, a stumble here and there, but overall fine. Its a mixed reef, with some softies, LPS, and SPS's. For the last 2 months, I've been battling an outbreak of green hair algae in the display, and its getting worse despite my efforts so far. Tank parameters have stayed the same, no major additions or subtractions. Automated water changes of about 3%/day, automatically dosing 2 part. Everythings on the money as far as test kits go. Here's some shots, sorry for the blue quality, only iPhone photos for now.

Full tank shot


Problem areas


Have been reading about algae scrubbers and the great success many have had, so thought I'd give this a try. My phosphate and nitrates have never been high, but I assume that I'm getting some leaching from the dry rock I used for the base. The green hair must be chewing them up. I built the scrubber feeding off a T on my return pump. Perhaps not ideal, but it was the easiest and least invasive method right now, plus I had the room. As you can see, the scrubber hangs over my center sump section. Its approximately 8 x 11 inches, and lit on each side by a 23W CFL 2700K in a reflector about 3-4 inches away. Flow is adjustable, and right now water cascades down both sides completely running over the mesh. As an aside, I have been using filter socks, a skimmer, a chaeto algae ball, and a combo GFO/carbon reactor since tank start up, and these current remain in place and active.

Sump with algae scrubber


I'll try to continue to post updates as it matures. Please comment and let me know your thoughts on my setup. Hopefully this green algae will finally be on the run, at least in the display tank!

Thanks for reading. Regards.

[Floyd R Turbo]

Looks like a good start.

How big is the screen?

How much water flow do you have going across it?

How much are you feeding?

[1cooljeep]

Screen is almost 8 inches wide and about 10 inches tall. Lit both sides. I feed 1 cube frozen in the mornings, and probably the equivalent in flake in the evening. As far as gallons per minute, couldn't say exactly. Not a lot of room to catch a representative sample of any size to know. I can turn it higher or lower based on a ball valve. The water flows over mesh pretty briskly. Any more and it splashs off sides.

[Floyd R Turbo]

Looks like you built this based on the tank volume sizing guideline. The newer guideline is based on feeding. 12 sq in of screen per cube of food fed per day, lit on both sides with 12W total light.

The flake food equivalent of 1 cube is about 10 pinches. That's a lot. So I would venture to guess 2 cubes/day would be adequate, and 3 cubes/day would be more than adequate.

This reduces your needed screen size down to 24-36 sq in from 80 sq in. Also, the amount of wattage you are currently using is low, 46W total on a 80 sq in screen - should be more like 80W. So reducing the screen size to 36 sq in puts you right where you should be.

The reflectors you are using are more conical than domed, so you don't get much spread on the large screen. Growth will be less effective around the edges, but for a smaller screen as outlined above, they would probably work well. Light are nice and perpendicular to the screen, that's just right.

All in all, I think yours should work well, so I would just keep it as-is for now, and if you start to notice problems getting good growth, etc, you might consider the above changes

[1cooljeep]

Thanks for the feedback. Initial deign was based on tank size. I've seen the feeding guideline since. To avoid other plumbing, the slotted pipe needed to do an "up and over". As a result, it's 10 1/2 inches above the sump water level. So unfortunately, that dimension is fixed if I want the bottom of the screen in the water. I'll leave it as is for now as you suggested and see what happens. My question is, what's the thought on proportions? Is any 40 square inches equivalent, even if its 4x10, 10x4, or 6.25x6.25?

[Floyd R Turbo]

If you have the screen extended so that it goes silently into the sump, that's fine, it's just not "effective" growth area. Which is why I said to leave it as is, because your effective growth area is where the lighting is strong, so as long as you know the limitation and don't expect it to be able to handle 8 cubes/day, you're fine. But you can likely make it narrower and concentrate the flow a little more where the light is best.

As for dimensions, generally wider is better if you have the flow available, but once the screen is cured up you can take a narrower screen and increase the flow over 35 GPH/in. But with the increased flow you can have an increased chance of spray, meaning you will need to have spray protection to keep water where it should be. Once you have that in place, crank it up.

[1cooljeep]

I've had the scrubber up and running now for about 2 weeks. Thought I'd show off some pictures of the growth so far. From what I've seen from other postings, looks like the growth on the screen is ok. Its light green with some darker green in spots, and definitely has a hair like quality to it. Opinions?

Scrubber growth 2 weeks


Screen prior to cleaning


The GHA in the tank is still terrible as you can see from the photos, especially of the powerheads. I cleaned all three of the powerheads 1 week ago. Its definitely getting worse. I read somewhere that things can get worse before it gets better. Maybe that's just where I am right now.

GHA in the tank


I scrubber the screen down to leave just some green algae in the holes and got in running again. Going to run some chemistry today and see where things stand, too. When I started this process, I remember reading somewhere that you shouldn't remove too much algae from the display tank when starting an algae scrubber up. So I didn't. Now that its been going 2 weeks, do I bother cleaning the power heads and physically removing any GHA I can from the display? Or, do I just let it all sit there and hopefully starve? Advice?

Thanks.

[SantaMonica]

I wouldn't remove anything from the display.

If those are the lights you are going to use, I'd decrease the width of the screen to match the reflector, and tape up the remaining slot.

[1cooljeep]

I'm into week 4 or 5 running my algae scrubber, but whose counting...

My display tank is still overrun with the green hair algae, but if I allow myself to be optimistic for just one second, perhaps I can imagine that things are getting slightly better.

First, the algae growth on the scrubber screen is filling in quicker. Here's a shot after just 5 days. I was taking me 2 weeks to get this much growth initially. Sure, its not 200-400 g like some people are pulling out, but to me it seems like there's good solid green growth after 1 week. And I'm oversize on my screen, some perhaps thicker growth would occur were the screen smaller. Not sure.



The green algae continues to be everwhere, but it doesn't seem to be coming back so fast and thick like it was. I use and automatic water change system and an auto top off system, both from converted grey plastic trash cans. I'm almost empty with this batch, and I'm going to give them a wash down before refilling either this time. Don't know if this is a continuous source of significant phosphates or not, but couldn't hurt I guess. I've heard arguements both ways. Basically, I'm just being patient and waiting for the system to stabilize, hopefully in my favor and not the algaes.



Thanks.

[SantaMonica]

Yea the screen does seem lacking in nutrients to grow. I'd cut it in half and apply all the flow to it. Once the thick green fills in, the photosynthesis will be strong enough to overpower the photosynthesis in the display.