Brown algae in the tank

[sashimimaster]

+1

Also putting lamps in between parallel screen is not very efficient, because you cannot easily reflect/redirect the light that goes sideways from the lamps in the middle - effectively, you are losing 1/2 of the light that radiates sideways from those lamps (parallel to the screen). So your 4x22W = 88W in the middle is really only 44W effectively, if that. Meaning you are now super-really-under-lit.

One screen, lit on both sides, with good reflectors. You didn't mention if the 55W lamps had reflectors - do they?

But there are screens on both sides of the lamps in the middle. The screens are sandwiched between the lights. The 55w lights do have reflectors.

[kotlec]

If I have too much screen does that mean too much filtering?

Not at all.

Only weak algae is growing on oversize screen and its not filtering strong.

[sashimimaster]

Here some pics of my set up. This is after 7 days growth.

[SantaMonica]

Well had you posted these at the beginning, this would have been easy. You need to clean the slot each time that you clean the screen; meaning the pipe needs to be removed and brushed with a brush. Not cleaning it is the reason you are losing all that flow... and filtering. No telling how much stuff is dying inside that pipe.

Also the outside of the screen practically has no light at all; most of the screen is not getting any light, regardless of what you see with your eyes.

So tear it down and build what I posted above.

[sashimimaster]

Well had you posted these at the beginning, this would have been easy. You need to clean the slot each time that you clean the screen; meaning the pipe needs to be removed and brushed with a brush. Not cleaning it is the reason you are losing all that flow... and filtering. No telling how much stuff is dying inside that pipe.

Also the outside of the screen practically has no light at all; most of the screen is not getting any light, regardless of what you see with your eyes.

So tear it down and build what I posted above.

I do clean the slot each time. I make sure there isn't anything clogged inside. I can't increase the flow because my pump can't pump it back into the tank faster than it drains and the scrubber would over flow.

How can I possibly not get any light? The lights are like 3 inches away from the screen.

[SantaMonica]

Only the area 2" from the T5 bulb is getting enough light. That screen need at least another bulb above and below the current one; preferably two.

Reduce the size so that the pump can supply more than 35 gph per inch.

[Floyd R Turbo]

But there are screens on both sides of the lamps in the middle. The screens are sandwiched between the lights. The 55w lights do have reflectors.

Same explanation - the lamps in the middle emit light in a radial pattern in all directions. For simplicity, let's only consider the horizontal pattern. Looking from the top down, imagine lines emanating outwards radially from the lamp. Notice that some lines hit the screen directly, others at angles, others at extreme angles, and other hit the other lamps. Only the lines that hit the screen at about a 45-60 degree angle or greater (up to 90, which is directly in front of the lamp) are really doing anything. The rest is lost. So you have a 22W lamp, and for simplicity let's just say that 5W of that is hitting one screen, 5W hitting the other screen, and 12W is lost. If you took that same lamp and put a quality reflector around it and re-directed the light all in one direction, you might get 80% of that light properly re-directed. This is why sandwiched screens are underpowered, unless you cram a bunch of lamps in there, which is still highly inefficient but overall more effective.

Well had you posted these at the beginning, this would have been easy. You need to clean the slot each time that you clean the screen; meaning the pipe needs to be removed and brushed with a brush. Not cleaning it is the reason you are losing all that flow... and filtering. No telling how much stuff is dying inside that pipe.

Also the outside of the screen practically has no light at all; most of the screen is not getting any light, regardless of what you see with your eyes.

So tear it down and build what I posted above.

Yup.

I would add that if you are indeed cleaning the slot, then possibly your slot is not wide enough or not straight enough, or your screen is 'wavy' in the slot, which can happen with longer screens, the water flow pushes the screen against the slot edge and blocks the flow. Could be that your screen is a little longer than the slot also - it should not be sung on the ends, there should be a very slight amount of play. Also you mention you can't increase your flow - I think this is a factor as well in the striping effect.

Only the area 2" from the T5 bulb is getting enough light. That screen need at least another bulb above and below the current one; preferably two.

Reduce the size so that the pump can supply more than 35 gph per inch.

Also agreed, I would remove one screen put the T5 on the other side with the other T5, and all the CFLs on one side with dome or side reflectors and put all available flow through one slot pipe. Better yet - put 3 T5HOs on each side (still only one screen)