Diatoms... what are they? how long do they last?

[sandypants]

So after tediously buffing off each leaf of my plants last night (vals, swords, java fern) I am beginning to wonder about these things I hear are called "diatoms"- read up on some other posts and people talk about them going away after awhile and are only in NON-mature tanks? I have brown algae on all of my plants (and on rocks and sand)minus the new shoots/leaves. I have had my planted tank for about 6 months and in the last month or so the algae seems to come at an alarming rate. I thought it was the change of season and perhaps the room with my aquarium gets too much light now (although sunlight is indirect where tank is). Anyway now I'm wondering if it is the diatom stage I have been reading about... how long does it last and how do I know if my tank is going through it OR if I need to make some adjustments to lighting/move tank itself?

[PostalPenguin]

Diatoms in an established tank can be a sign of old bulbs. You may need to replace the bulb in your tank. In a new tank they usually go away on their own after a few weeks.

[sandypants]

Ahhhh that could be- thank you PostalPenguin . I have not replaced the bulb since I got the aquarium in Feb (and it was used although LFS I bought it from said light looked "pretty new") I actually stated a thread on here awhile ago about bulbs and when to change them- I think the consensus was wait until they go out on you to avoid drastic light changes for the plants (in retrospect doesn't make much sense if you are just going to change it out from a dead one to a blazing bright new one anyway). Guess it's time to figure out which kind I need

[Mith]

New bulb? What's the theory behind that?

I have found leaving my lights on a lot causes that kind of reaction.

My otto does a marvelous job keeping my plants clean!

[Northernguy]

Light bulbs lose their intensity after a while and should be replaced every so often.Brown diatoms is a sign of that or not enough light.It also indicates too much silicates in the tank.
http://plantgeek.net/article_viewer.php?id=9

[PostalPenguin]

As bulbs age their wavelength emissions change, shifting the light towards the spectrums that algae use and plants do not.

CFs are recommended to be replaced every 6 months, T5s every year. However, a low light tank probably wont have a noticeable impact from old bulbs but a high light tank may suddenly start having problems.

Some people have also had success getting rid of diatoms using phosphate absorbing resin since it will absorb silicates as well.

[sandypants]

Thank you to those who have responded.

Northernguy- I just looked up silicates but am still confused- (not a technical person AT ALL) where do the come from? Is it in the water???

[Northernguy]

I am not sure as to what they are.I do know that they leech in from some substrates and they mostly come in through your tap water.
Dave 66 may have an answer to that question.

[domjd05]

silica is found in rock and are what makes up most of the sand people use for aquariums.

[sandypants]

Hmmm so even the over-priced 5lb $8 bags of "aquarium sand" I purchased from the LFS have silicates? And they will eventually go away??