Lets see...
Originally Posted by pskelton
I have been for 6 months now and all I get is black/brown algae. Early on the implementation of the scrubber was a last resort to save me from several system design mistakes which brought my nitrate above 160 PPM. Long story short water changes were not making any long term affects and a limited aquarium budget I decided to try an algae scrubber. With in a few weeks of install my nitrate dropped to 40-50 PPM and finally after 6 months of running my nitrate is a solid 0 PPM. I am sure it could have happened faster if I had used brighter lights but that fact is it worked and my tank is very healthy today.
That's a great success story, thanks for sharing!
My scrubber (See pic for reference)
Now I am looking to improve the performance of my algae scrubber. I have never had anything other than black/brown algae even after adding iron. The flow over the screen is 35 gal/min/in as recommended. This is a 55 gallon tank, the screen if 6.5 in wide and it extends a good 14 inches into the bucket. Only about half the length of the screen gets direct light, so the directly lighted section is approximately the right amount of square inches. I am running two 23watt CFLs which I realize its a little under powered for a 55 Gallon tank but I am very space limited and the 23 watt bulbs fit the reflectors perfectly.
I am sure that I could add more bulbs or increase the watts and I would probably start growing green hair algae but I was wondering if there are any other changes I could make to get the same affect.
I looked back at your pic, I don't see anything glaringly amiss with your setup. Your flow is right, the lighting is right and perpendicular to the screen, the reflectors are decent. Your scrubber efficiency may improve by increasing the wattage of the lamps and decreasing the photoperiod. I posted this a ways back and will post is again shortly. This type of approach can help push through the brown/black algae.
A couple questions I have are as follows:
1) I can not cut the length of the screen down since the length of it is to prevent splashing into the bottom of the bucket. Should I place a shield over the bottom half of the screen to prevent the spill over of light from getting to the screen? Would this buy me anything?
Don't worry about excess unlit or poorly lit screen. The algae in the highly lit area will naturally out-compete this algae, though the algae in the lower-light area will probably grow brown. Generally not a concern, but blocking is can't hurt, just probably not really necessary.
2) Should I cut a new slot pipe for a narrower screen and design my screen dimensions around 2 23 watt bulbs instead of the size of my tank?
It would be better to increase the wattage to match the screen
3) My screen is not the recommended size needle point mesh it once size smaller (smaller holes). I already have a piece of the recommended screen standing by, should I start a new screen with the recommended material?
If you used #10 mesh (10 holes per inch) instead of #7 (7 holes per inch), I think you're fine.
4) My screen has been dominated by black algae for 6 months (when the nitrates where above 0 I was cleaning the screen every 3-4 days). Could it be that my screen after being dominated by this type of algae for so long is unable to let the green algae take root? Should I start a new screen?
Maybe. What I would try first is taking a stiff-bristled brush and cleaning very thoroughly on one half of the screen, getting all the holes cleared out and everything. This will in effect re-start a portion of your screen, though it won't be a complete re-start, because you're leaving something behind.
All of this begs the question though - is there something wrong with your system that is raising these concerns, or do you just want to see green growth?
I don't always have green bushy growth on my screen, there are weeks where it grows a lot darker and slimier, and I had some algae in the DT. Some of that had to do with the fact that I had severely coralline-encrusted powerheads, a ghetto temporary setup, and I allowed some of my levels to get out of whack 'cause I've been too busy lately, and I recently discovered that the Workhorse ballast that I have is probably not the best ballast, which means I need to switch that out and get a more efficient one that will drive the lamps harder (I think the one I have is wearing out)
But my point is, if your water parameters are fine, fish & corals are happy, DT is free of algae, they what's the worry?
I am open to any and all recommendation. Thanks in advance.
You're welcome...HTH