Brown Hair Algae

[schmath]

Anyone know what I’m doing wrong to get this brown hair algae and why I have no nitrates? I have a low tech 5.5 gallon tank with 2 sponge filters and UNS Controsoil substrate planted with anacharis, pearl weed, and Anubias petite. I’ve have diatoms for the life of this tank (maybe a year?) I tested for silicates, and sure enough, my tap water has a little. So I tried pre-filtering water for water changes with phosguard, but I knew I couldn’t do that long-term, so I just put the HOB with phosguard right in the tank for a week. I didn’t leave it in because the HOB was too strong for my betta, but ever since I took it out, I’ve had this brown hair algae. I just tested my water after not changing the water for 10 days and the ammonia, nitrites, and nitrates were all at 0!? I retested the nitrates, carefully following the directions, and still 0. They’re usually at least 10 or 20 and I expected them to be on the high side since I’d put off the water change. So after the water change I added .5 ml thrive. I hadn’t been fertilizing to see if that made a difference. The old growth with the algae on it looks melty, but the new growth is green and algae free even without fertilizer. The light is on for 5 hours/day and the tank does get some sunlight when the blinds are open, maybe a couple hours/day. The tank went through a rescape/substrate change and subsequent minI cycle a few months ago.

 

[CheshireKat]

The algae is probably using up the nitrates. Maybe the light is too strong? The sunlight in particular, although I get no algae from the sunlight (unless my platies and mollies eat it before I see it).

 

[schmath]

The algae is probably using up the nitrates. Maybe the light is too strong? The sunlight in particular, although I get no algae from the sunlight (unless my platies and mollies eat it before I see it).

I've suspected my light was too strong for a while. It's a Finnex Stingray and is supposedly good for low/medium plants, but I think it's too much for my little tank. I should have gone with a light with a dimmer.

 

[CheshireKat]

can you get a dimmer/timer to plug into the light? That's what I did with mine. Alternatively, you can raise the light up so it's not so intense and close to the aquarium?

 

[schmath]

Update: hair algae is mostly gone. I'm not sure what made the difference, but the changes I made were
1. I lowered my photoperiod to 4 hours/day,
2. I turned down the heat to 79, and
3. I started dosing .5ml thrive after each water change.
Still lots of diatoms, but there are silicates in the tap, so I don't expect them to go away. They've been present for the whole year I've had the tank.

 

[schmath]

Oh, also I lowered the water level down about an inch below the lid. (just because I didn't have enough treated water on hand to fill it completely.) I don't know if that made a difference, but the algae disappeared almost overnight after that water change, so maybe?