Brown algae in the tank

[sashimimaster]

So I have a 680 gallon tank. I'm running an ATS with 2 screens that are 30x12". There are 4x22w CFL bulbs at 4000k with 2 more 55w flourescent bulbs. I run it about 7-8 hrs/day. My nitrites are zero and the nitrates are under 10. I clean my ATS weekly. The green algae that's growing looks a little slimy and dark. There are only 9 fish in the tank totally around 50".

The problem I'm having is I'm getting brown algae in the display tank. It's covering most of the bottom of the tank where the sand has blown off and is bare. Why am I growing algae when I have a scrubber and my water parameters are good? Am I not putting in enough light into the display tank?

I have been feeding more recently and the fish are getting a little bigger. But with 680g and another 150g in the sumps I would think it shouldn't be affected that much. I don't do too many water changes since I figured the ATS should minimize that. But lately I've been changing about 25% / week.

Any thoughts?

[SantaMonica]

Welcome.

Gallons and waterchanges do not matter. The problem is your very weak scrubber lighting.

How much are you feeding?

[sashimimaster]

Welcome.

Gallons and waterchanges do not matter. The problem is your very weak scrubber lighting.

How much are you feeding?

Really? Each of my CFL are equivalent of 100w incandescent and the 55W CFL is like 200w. When this thing is on it's like a solar flare.

I was feeding only twice a day on weekends. On weekdays only once a day. I've since cut it back to once a day.

[SantaMonica]

Each 30 X 12 = 360 square inch screen needs a total of 360 real watts, preferably in a 2-sided configuration, for 18 hours a day.

Yours has 4 x 22 watts + 2 x 55 watts = 198 watts, a little over half of the minimum. And less than half of the hours. So at best you have 1/4 the photosynthesis you need.

[sashimimaster]

I made a mistake on the amount of time. I'm running it from 6p to 1p the next day. So 19 hrs / day.

Let's talk in terms of lumens. Each 22w bulb puts out 1500 lumens and the 55w puts out another 3900 lumens each. With 2 two sides screens that's still not enough?

[SantaMonica]

Ok so about half the minimum photosynthesis you need.

Not nearly enough lumens.

[sashimimaster]

If I'm only making half of what I need I can't run it 24/7. So the only way is to increase the lumens? I could have swore I calculated it correctly. Maybe I didn't rough the screen enough or have enough flow.

At some point it would cost more in electrical energy than just changing water.

[SantaMonica]

Two screens of 30 X 12 is 720 square inches, which is sized for 60 cubes a day.

[sashimimaster]

I've added more light but the brown keeps increasing. I've heard that scrubbers dont remove silicates and the brown feeds off of silicates. Is that true? Is it possible that I don't have enough flow?

[SantaMonica]

Nothing to do with silicates.

Even with enough light, If you are not feeding at least 30 cubes a day, it will only grow a thin brown because there are not enough nutrients. You never said how much you feed, so there is no answer to how big the scrubber should be.

[sashimimaster]

So you're saying I don't feed enough? The algae on the scrubber is green slime and more than a thin coat. I brush it off every week.

I don't measure how much I feed by cubes. I can estimate I feed about 2t of Hikari sticks and about 4 cubes of diy fishfood.

Could it possibly be from my driftwood leeching something? When I rub the algae it comes off easily almost like powder.

[sashimimaster]

here's what it looks like now.

[SantaMonica]

Well I don't know what 2t is, so I still don't know the feeding.

Need pics of the screen before you clean; several with different lighting, and some closeup to show the texture.

[Floyd R Turbo]

So I have a 680 gallon tank. I'm running an ATS with 2 screens that are 30x12". There are 4x22w CFL bulbs at 4000k with 2 more 55w flourescent bulbs. I run it about 7-8 hrs/day. My nitrites are zero and the nitrates are under 10. I clean my ATS weekly. The green algae that's growing looks a little slimy and dark. There are only 9 fish in the tank totally around 50".

The problem I'm having is I'm getting brown algae in the display tank. It's covering most of the bottom of the tank where the sand has blown off and is bare. Why am I growing algae when I have a scrubber and my water parameters are good? Am I not putting in enough light into the display tank?


Each of my CFL are equivalent of 100w incandescent and the 55W CFL is like 200w. When this thing is on it's like a solar flare.

I was feeding only twice a day on weekends. On weekdays only once a day. I've since cut it back to once a day.

Ok, so to summarize:

2 screens, each 30x12 = 360 sq in. Total of 720 sq in of screen. Seems like you sized this according to the old volume-based guidelines, correct?

Scrubber Lighting: do you have 4x22W + 2x55W on each screen? On each side of each screen? Please provide the total wattage of all lamps used on the entire scrubber system. As described, it does sound under lit per SMs evaluation.

Feeding: Need to specify this a little better so we can help you figure this out. Right now it sounds like you are feeding much, much less than the scrubber capacity, as SM mentioned.

Type: is this Freshwater or Saltwater? Looks like FW to me. FW scrubbers are a slightly different animal so this matters.

In summary - I'm guessing that the reason you are getting poor growth is because your scrubber is sized incorrectly (according to the new guidelines from over a year ago).

So it's not that you need to feed more, it's that your scrubber don't grow right with the current feeding level because of the size. So if you want to get green growth and better filtering, and keep the feeding the same, you will likely need to reduce your screen size in order to compress the growth area down and force green growth, which filters better.

At the outset, without any additional information, I would say that you should start by removing one of the 30x12 screens and taking all the lighting from that screen and putting it on the other screen.

[Floyd R Turbo]

Also pics of the setup with and without the scrubber lights running are really needed here.

[sashimimaster]

Well I don't know what 2t is, so I still don't know the feeding.

Need pics of the screen before you clean; several with different lighting, and some closeup to show the texture.

Two teaspoons of Hikari Sticks

[sashimimaster]

Ok, so to summarize:

2 screens, each 30x12 = 360 sq in. Total of 720 sq in of screen. Seems like you sized this according to the old volume-based guidelines, correct? "Yes"

Scrubber Lighting: do you have 4x22W + 2x55W on each screen? On each side of each screen? Please provide the total wattage of all lamps used on the entire scrubber system. As described, it does sound under lit per SMs evaluation. "That is the total amount of light in the scrubber. It is sandwiched between two screens. 1 X 55w each on the outside and 4X22w down the middle."

Feeding: Need to specify this a little better so we can help you figure this out. Right now it sounds like you are feeding much, much less than the scrubber capacity, as SM mentioned. "I feed one square tube of food appoximately 4"X1/2"X1/2" and 2 teaspons of Hikari sticks per day."

Type: is this Freshwater or Saltwater? Looks like FW to me. FW scrubbers are a slightly different animal so this matters. "Yes freshwater."

In summary - I'm guessing that the reason you are getting poor growth is because your scrubber is sized incorrectly (according to the new guidelines from over a year ago).


Please see my answers within your questions.

[SantaMonica]

2 teaspoons = 10 ml = about 3 cubes. So you are feeding about 7 cubes a day. Way too little for your size screens, if you are feeding this every day. If you are not feeding this amount every day, your screen are way way too big. Without seeing a pic of your screens, I can say that they'll will be a light brown coating that never goes green.

You need 7 X 12 = 84 square inches, and at least 84 total CFL watts. You are currently running 200 watts. Do this:

Get rid of one screen. Cut the other screen vertically so it is 7 inches wide, and 12 inches tall. Tape up the remaining slot. Put 60 watts of light on each side, reflected so that all the light hits the screens. The total will be 120 watts; disconnect the remaining 80 watts. Run the lights for 18 hours, for 14 days.

[Floyd R Turbo]

+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?

[sashimimaster]

2 teaspoons = 10 ml = about 3 cubes. So you are feeding about 7 cubes a day. Way too little for your size screens, if you are feeding this every day. If you are not feeding this amount every day, your screen are way way too big. Without seeing a pic of your screens, I can say that they'll will be a light brown coating that never goes green.

You need 7 X 12 = 84 square inches, and at least 84 total CFL watts. You are currently running 200 watts. Do this:

Get rid of one screen. Cut the other screen vertically so it is 7 inches wide, and 12 inches tall. Tape up the remaining slot. Put 60 watts of light on each side, reflected so that all the light hits the screens. The total will be 120 watts; disconnect the remaining 80 watts. Run the lights for 18 hours, for 14 days.

Actually the screens are a deep green. A little slimy but green. I think the flow is a little lacking.

If I have too much screen does that mean too much filtering? Then I shouldn't have any brown algae at all right? My thought that it wasn't scrubbing enough is why I'm getting 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)