There was just a thread about brown algae, but I didn't want to take it over with my own questions. Plus my situation is a bit different.
I have been battling Brown Algae in my divided 10 gallon. It has been cycled for a few months now. I use silk fake plants and sand. For lighting I use two Aqueon Daylight/Bluelight Mini Compact Fluorescent bulbs at 10 watts each. The light is on for 12 hours each day. I bought two marimo mass balls and put one on each side of the divider thinking it would starve the brown Algae, but have had no such luck. It is getting really annoying because it is starting to stain my light colored silk plants. I would really appreciate any tips you may have.
Something that may be contributing is the fact I use a buffering powder to stabilize the pH. I'm not sure though. I do have some AlgaeQuel that is supposed to stop all Algae growth, but I would like to avoid using it if I can.
Your problem is how long the lights are on daily. Lights should only be on 8 hours in non planted tanks as there is no way for anything to use the nutrients that algae thrives on. My recommendation would be to lower your light to 8 hours and see is the benefits your situation
It's not just the length of your light, it's also the kind of lightbulbs you're using. They're 'daylight bulbs' and from what I've come across, daylight bulbs have the right amount of kelvins to provide nourishment to anything that photosynthesizes.
You should definitely lower the amount of hours your light bulb is on as was recommended by Mo. You have a couple of marimo, but they're low light and low maintenance, so they will do just fine with 8 hours. Usually when growing plants, you start out at 8 hours and then work your way up to 10 hours- 12 being the maximum time, but that also depends on the plants that are in your tank as well as finding the 'sweet spot' where your plants thrive, but little to no algae is able to thrive.
Another thing you'd want to do is start scrubbing your tank and decorations- get an unused toothbrush or something so that you can go over and use elbow grease. It really goes a long way when trying to maintain algae and your work will definitely pay off so long as you keep up with it.
Other than that, the reason why your marimos haven't been able to counter act the brown algae is because they're slow growers, therefore, they eat the nutrients in the water slowly... You also only have two in a 10 gallon, but if you want to make an impact on algae with plants you need to have enough in there to make the difference.... Usually faster growing plants like wisteria or duckweed are better because they're nutorious at eating up nutrients.
Brown algae usually comes along when your tank is newly established, so it makes sense that you have some. Don't worry, once you've found the balance and gotten used to how your tank works, the diatoms will start to go away until it completely disappears. Sometimes it comes back, but it's really more of an eye sore than anything...
Also now that I think about it, maybe more frequent and/or larger water changes? It also helps to keep down algae and you've only got two marimos at the moment so it's not too big of a worry if you do larger/frequent water changes...
How old are your light bulbs? The kelvin rating starts to diminish after as fast as 6 months, even if you can't tell. Brown algae most often grows in tanks with too little lighting, so if you have lights on for 12 hours a day and have brown algae, you may have bad lighting type for live plants. What are your nitrates also? It is very common to experience brown algae in a cycling tank. It thrives off of nitrates. Usually it dies off once the tank is fully cycled though.
What method are you cycling with?
My tank has been fully cycled for a few months now and I keep Nitrates at 10 ppm or below. The light bulbs are new, bought last month. I got them to replace the crappy incandescent bulbs that came with the kit. I had brown algae before buying the new bulbs though.
When you wipe it off, does it grow back?
Also, what brand is your pH buffer?
Brown algae also likes Phosphate and Silicates, which can also be found in water.. If you never had this problem, it could be something in the buffer. That's my best guess.
My bad, I always get the lighting issue with brown and green algae mixed -.-;; But yeah, Olympia has a point- they do thrive on little light and it really does depend on how old the bulb is to know whether or not the bulb is very effective.
Photosynthesis aside, they also get their nutrients from silica/silicates, nitrates, and phosphates so if it's not a lighting issue, it can also be from overfeeding or the need of more frequent/larger water changes...... Pretty much all these things can be introduced into the tank from unfiltered tap water if your tap contains silicates/phosphates/nitrates, so if it still seems like brown algae is an issue after trying to get rid of them for a while (which again to me it sounds like it's more because your tank is newly established so I'm sure this isn't something you'll have to worry about) then you should also take your water source into consideration.
I really appreciate you guys helping me figure out the cause of this annoying algae.
Yep, when I wipe off the glass and plants it grows back pretty quickly. It is mostly on the fake plants though. The buffer I use is called Gold Buffer. It is actually meant for Goldfish and I use it because out of tap the pH is around 7.8 - the Gold Buffer keeps it there instead of lowering it. It is a non-phosphate buffer.
I never have a problem with brown algae in my unfiltered tanks. It seems to always be the ones that are filtered and cycled. I don't overfeed and I do pretty big water changes, around 50% every week.
The sand... I bought in at a LFS and it didn't have a brand. I know that it is Black Tahitian Moon Sand though.
Tahitian Moon Sand is made from glass shards and contains silica. This is probably leaching into your water, feeding brown algae. It will eventually wear off if you want to wait, or you could try getting rid of it all. :) Just keeping more frequent water changes will be your best bet, besides ditching the sand.