Brown Spots all over tank

[SillySnail]

My 2.5 gallon tank develops brown scum like spots on the walls and plants after about a month since full tank cleaning. I do 40% water changes twice a week and have a small filter/bubbler. I scrub the plants and cave about once a week to keep things clean, but these spots still develop. I think it might be bacteria colonies or something.

I have one betta and one mystery snail in the tank.

Any advice or answers as to what this is??

[bahamut285]

It is probably just algae and/or diatoms

[HatsuneMiku]

sounds like diatom algae .. try reducing the amount of light your tank gets each day and see if that works

[Mo]

I would expect it to be diatoms or other wise known as brown algae, this occurence is very common in newly setup tanks presumably because of the unstable water parameters, amount of excess nutrients and the high phosphate level which they primarily thrive on, the high phosphate level is the primary cause on established tanks.

[Olympia]

At this point I'm going to point the finger three ways. Low light, high silicates, and a cycle trying to establish....
If lighting isn't a problem, we have to look at some other factors. Diatoms usually do best where phosphates are low and silicates are high. When it is reversed other algae can get a better hold on things. Your tank is still relatively new, I would wait a few months before declaring a silicate attack. Since your tank is small, I'd manage it manually for now.
Is it the kind that falls off easily, or the kind that is hard to scrape off?
Your Brig snail will not control your algae problems very well. In a small tank he may be of some use, unless the algae is the kind that is tough to scrape off.

[bellasia]

Hi

Had the same thing but since buying a couple of Marino Moss Balls for my tank its cleared up, used to be so bad and covered my decos and the sides.

[Pogthefish]

Sounds like diatoms, i had them too, just wait it out. After a few months they will go away.

[SillySnail]

it comes off easy, I used my soft bristle tank cleaning toothbrush and brushed it off with one swipe, and the tank does have a light over head which i often turn on, so ill keep that on less

[Olympia]

Might want to keep it on longer. Brown algae thrives in low light where other plants and algae can't.
I'd look into getting a Marimo ball or something. It might help a tad bit.