New Scrubber - No Green Algae

[regmo123]

Hi, having grappled with green hair algae in my display tank for almost 2 years, I've decided to shift from skimming to turf scrubbing on the advice of a few others who have made the same shift. Feels like a last ditch attempt to get my tank under control and in balance properly.

So - I'd appreciate some help from forum members. I've had my scrubber running for 6 weeks now and most of that time, I've been getting black/brown sludge-type growth. Nothing green or thick yet. Is this just a case of waiting longer for the green stuff to grow of should I be changing anything? I've attached some pics of the latest growth...

My systems specs are:-

240L display tank with Eco-Lamps KR93 LED lighting unit. Lighting running from 13:00 - 22:30 (phased moonlight - daylight - moonlight).

Turf scrubber has 31x12cm (12"x5") screen. Fed by 2000 kph (454Gph) pump flow. Lights are 3x8w t5 (3000k) (total 24w) each side of screen (ie both sides lit) with lights approx 4cm (1.5") from the screen.

Thanks for your help.

[SantaMonica]

Dark growth is always too-little light.

5 X 12 = 60 square inches = needs at least 60 watts light. You have 24.

[regmo123]

Thanks Santa Monica - appreciate the quick reply.

Can I just check that I've understood lighting requirements correctly. You're saying I need min 60W lighting - is that per side or min 30W per side of the screen? I have 24W per side currently.

If that's too low, what lights do you suggest (I'm using T5 units currently so would prefer to stick with those fittings if possible).

Thanks for your help.

[Garf]

Noticed you were hanging around on th UK algae scrubbers site and thought I would give you a nudge in this direction. As I remember, this was originally posted 5 weeks ago and you got no response. So, after 11 weeks is the growth the same as in the photo' ? Looks like you may also be getting flow problems from the slot, is it a drilled slot ? You could shade the slot to prevent algae growing down from the slot.

[regmo123]

Thanks for your 'nudge' - suddenly getting responses now I'm on this forum!!

The growth is pretty much the same - the pic on the left was taken last week and the others about 5 weeks ago - so it's still pretty dark and slimy.

Not sure what you mean by a 'drilled slot' (or what 'shading' might mean) - perhaps you could advise.

The slot was cut with a dremel-type tool I believe (I bought it ready-made from a supplier in UK so assumed it was good to go!!)

Thanks

[Garf]

For "shading the slot" I mean preventing light getting to the screen where it enters the slot. This reduces the amount of algae growing in the slot and helps prevent flow restriction from the rest of the screen. For mine I have used Perspex bent to form a "U" shape, then taped it up to prevent light going through. This is then placed ontop of the pipe, therefore shading the length of the slot from a lot of the light. There are other methods though.

For my "drilled slot" comment, as long as your slot is clean and straight it should be OK.

[SantaMonica]

Ok 2 X 24 = 48 which is better, but still needs at least 60, and more for high-nutrient or high-feeding systems.

Quick solution, cut the screen vertically to make it smaller, and tape off the slot.

[regmo123]

OK - I'll give that a try. What width do you suggest cutting out?

Appreciate the help.

[Garf]

How much are you feeding. 1 cube of food a day should be 12 square inches, not 12 inches squared.
If your lighting is the standard tube type, you're better off chopping some off the drop otherwise you'll lose the light increase per surface area. A pic of your display would be good.

[regmo123]

Thanks Garf,

I tend to alternate food - flake or pellet one day followed by 2 cubes the next.

I've attached a couple of pics of the tank (you'll see the algae and rear wall growth) - a bit light on corals so far as I don't want to put any more in until hair algae is under control.

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[Garf]

If you follow the recommended figures, you could get rid of 50% of your screen. Instead of cutting your screen, I would be tempted to try an oversized slot shading thingy as described above. Ie shade 2 inches of the screen from the slot pipe down, this can then be altered whenever you need to increase feeding. However, cutting the screen would be the tried and tested method.

[Floyd R Turbo]

Just a point, you do have green algae growth, I can see it in one of the pics. It's covered up by a slime layer. I get that too. Filtering is still pretty effective on mine even with that. I was running a shortened photoperiod, I bumped it back higher and my dark slime has dropped off a bit. Intensity is key.

[regmo123]

Thanks Floyd.

Sorry for the dumb question, but what do you advise to increase intensity on my setup?

[Floyd R Turbo]

can you bump the T5s to T5HO or are they already HO? Pics of the entire setup would help. Total lighting wattage is only one piece of the puzzle.

[tomservo]

I don't think there is such a thing as 12" T5HO, Floyd. He might be able to overdrive them with the right ballast, but adding reflectors if he doesn't have any would be a good option as well, if there's room.

I thought it was 1w per sq in per side?

[regmo123]

Floyd - I don't think I can get T5HO in 12" length (if you know where I could get them then let me know :) ).

I've added some pics - hope they help, if not let me know what would helpful to see and I'll take the right pics. These show the screen in operation and the general positioning and inlet to the ATS.

Tomservo - I've got reflectors behind the T5 tubes. They're 8W 3000k rating - any views on the lumen rating (is this correct for the ATS?)

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[Garf]

I don't think there is such a thing as 12" T5HO, Floyd. He might be able to overdrive them with the right ballast, but adding reflectors if he doesn't have any would be a good option as well, if there's room.

I thought it was 1w per sq in per side?

No, it's 1 watt per inch of screen whether 1 sided or 2 sided and that's why 2 sided is more effective I believe. You can do I watt per inch per side and half the photoperiod on 2 sided screens.

Regmo123 - how long are your scrubber lights on for?

[Floyd R Turbo]

Ok I was wanting to see if your reflectors and the rest of your setup were good. Looks good to me. It's not necessary to go HO but it helps increase light density if you can, otherwise you have to cram more lamps in the same area and use smaller reflectors - and you start approaching the point of diminishing returns.

3000K is right

You don't want to go double-lit and half the photoperiod on a single sided screen - can't use that 'rule'. Single sided is weak to begin with, you need the full photoperiod IMO.

The design guideline is 1W per dimensional sq in of screen, split between both sides. So 60 sq in = 30W per side. You're a little low, and one thing to consider that I have found is that in the center of the screen, the screen is getting light from all angles. Near the ends of the lamps, there is a sharp intensity drop-off and the screen is only getting about half the light. I trimmed my screen down so that the length is 1" shorter than the actual glass part of the lamp on both ends. I was only getting darker red turf in that area anyways, which grows better in lower light apparently, and after cutting that area out it did not return. So I would consider shortening your screen. This mean of course cutting a new slot tube, but it will also increase your flow rate per unit length of screen

[Garf]

I have been looking at a UK reefing site and I think I have found the place you bought your scrubber from. Have been looking at other examples and they all seem to be suffering from low flow problems. Your pump is 2000lts/hr but probably not delivering that to your screen with head loss etc. Other people with identical units are growing algae into the slot further reducing flow. The lighting units are only delivering 1100 to 1200 lumens per side, this also seems low ( 2 x 20watt cfls can deliver 2200 lumens ). JUST FOOD FOR THOUGHT.

[regmo123]

Thanks Garf - interesting stuff.

Based on your review of the unit, what's your view of the changes I could/should make to boost algae growth? I don't really want to change the lighting units as they fit well into the ATS housing. I've just changed bulbs (previously 3500k, now 3000k) but not sure of lumen value (I'm guessing probably 400 lumens per tube) - how can I work that out?

I did see somewhere else on the forum that plant growth T5's are recommended but I'm not sure if the kelvin rating will be too high (eg Gro-Lux 8w). Views?

Thanks

[Garf]

Listen to Floyd and SM. They are always spot on. They have a lot more experience at this than I do. However, please shade the slot!

[SantaMonica]

it's 1 watt per inch of screen whether 1 sided or 2 sided and that's why 2 sided is more effective I believe.

Yes, because the roots get light from both sides, and can survive twice as many days before running out of light and dying and letting go.

[regmo123]

Garf - I'm running the ATS lights 18 hours on/6 hours off.

[Garf]

Can you check the distance the bulbs are from the screen, and get them closer? Actually measure the distance and not estimate, from the bulbs, not to any splash shielding.

[regmo123]

It's approx 5cm from the the bulbs to the screen

[Garf]

Is water pouring off the bottom of the screen in one continuous sheet ?

[regmo123]

It's not really possible to tell, Garf as there about 1" of water in the bottom of the chamber and the bottom half inch of the screen sits in the water (so can't tell how the water is flowing off it).

As for shading the slot - any idea where I can the right sort of plastic/perspex from and how i can shape it to fit?

Thanks