How high should my light be above my substrate?

Bluydgrl

I have a 36 gallon freshwater Bowfront with a Coralife dual light fixture.The bulbs are colormax 31W T5H0 and the other is 6,700K T5HO.I have a sanded bottom with a lot of live plants.
I'm getting hair algea on my plants and it wont go away.I run my light for about 10-12 hrs a day.Tank sits across the room from a window but I have the shaded turned so the light isn't hitting it directly.When i'm home and it's pretty light in the room I will turn my lights off until the sun moves.
I was thinking my light might be to close to substrate or I have the wrong bulbls in it.I have Oto's to take care of the other Algea I get.It's just the hair algea I don't like.Is there also a fish that will eat this alge?

JDM

Can't comment on the light fixture itself but typically they just sit on top, distance to the bottom is fixed and you are better to adjust duration of the light first. I think that 10-12 hours might just be too long in your situation, I read others that are as low as 8 or 9 hours. I do well with 14 hours but I run LEDs and that period seems to just work well for me... each tank balancing act is different.

If the fixture is too much, changing to a lower wattage or different diameter bulb might be in order rather than raising the fixture... others can comment better on that.

Jeff.

Bluydgrl

Posted via Mobile Device

BarbH

I would definitely decrease the amount of time that the lights are on for. Are you using CO2, in this tank? When I was running my 50 gallon planted I had my lights on for about 8 hours a day and that was with using a single T8 fixture. Those T5ho are putting out a lot of light and you are getting imbalance of light and nutrients I would think.
Posted via Mobile Device

Bluydgrl

No CO2..Just Seachems Flourish every 2-3 times a week.Do you think I should go with different bulbs?Just would hate for my plants to die on me
Posted via Mobile Device

BarbH

What type of plants do you have in your aquarium? I would personally start by reducing the amount of time that you have the lights on for and see if that helps with the hair algae issue. You might find that you will need a different fixture, but first I would start with the duration of the time that your lights are on and see how that works. You also mentioned that the tank is across from a window, what direction is the window facing? Even with having shades drawn across the window you could be getting quite a bit of light coming in from there.

Byron

Others have correctly identified the issue and how to fix it. I've done a fair bit of experimenting with this problem which I have also had (but no longer).

The first step is to reduce as much as possible the ambient daylight, especially if it is direct sun. And to illustrate how this can impact: I noticed for 2 or 3 years that brush algae (I am thinking this is probably what you are referring to) always took off in the summer. It finally dawned on me that the brighter and longer daylight could be the reason, so for the past two summers I kept the windows covered all day with both shades and heavy drapes. End of algae increases.

Second issue is the brightness of the tank light. Here, before considering different light (which would mean either T5 NO tubes as you now have HO, or a new fixture altogether), I would lessen the duration. I have my lights which are T8 and moderate, on for no more than 8 hours daily; any longer and brush algae increases again. You can go down to 6 hours daily, according to George Farmer. I would reduce down to about 8 and see if it helps.

You won't see the existing algae disappear, but the goal is to not have it increase further.

Byron.