Clear / white algae?

[often dignified]

On my 5 gallon stocked full of snails (added 4 dwarf puffers tonight ), I've kinda been fighting a sort of clear algea. It looks like brown algae, but it doesn't really have any color.

Is it diatoms? When I wipe it away w/ a paper towel, it feels kinda gritty. It's a acrylic mini-bow so I'm worried about scratching the acrylic.

Anyone know of ways to get rid of this? My water parameters are perfect and I do weekly or even twice a week water changes.

 

[Rocketman]

It could be minerals that build up (a lot of people complain of these on their heaters.) I'm not sure what causes it though. Does it flake when you scrape it off and you have to fish it out?
4 Puffers may be a lot for that tank as well.

 

[fishfood]

Diatoms are usually very brown. it doesn't sound at all like diatoms. I agree, that it might be a mineral thing. There is also a hair algae that looks white but it's not a film.