An observation

[Sacha]

Just a personal observation...

I have had diatoms growing on my tank walls, and on the Staurogyne Repens for months now. The diatoms is only present in the shaded areas of the tank, mostly on low leaves that are shaded by the higher leaves.

After struggling for literally months trying to improve flow/ distribution (my turnover is 24x and the fish are nearly being blown away), I decided to take a different approach.

So I increased my photoperiod by 1 hour, (and didn't change anything else), and now the diatoms are disappearing. They haven't just stopped growing, they're actually disappearing.

Hope this helps people in a similar situation

 

[roadmaster]

Am pleased this worked for you.
Seemed to work in opposite for my low tech tanks.
Increasing the photoperiod normally induced more diatom's for me, along with various form's of other algae.
I don't use CO2 or supplement's thereof, so I fear I am using all the light I can without encouraging problems.
Perhaps the diatoms retreating were assisted by bacterial activity that was slow to develop and happened to coincide with you increasing the photoperiod?

 

[Sacha]

I'm going to cautiously suggest that this wasn't "just coincidence".

The tank is about 4 years old, very mature and stable. It's pretty much stayed the same for months. Any bacterial colonies will have developed by now.

 

[roadmaster]

Well then perhaps you finally got CO2 dispersion at optimum levels for current condition's which made thing's uncomfortable for the diatom's.
I see mention made in previous post's of switching CO2 from output to input line of filter.
Perhaps the gas is getting chopped up better and better distribution throughout the tank with this change.
I would not personally place much hope of decreasing diatoms by increasing light intensity or duration.
Have set up lot's of tank's in forty plus years, and have never seen more light to be the answer when trying to encourage the withdrawl of diatom's.
Usually just time going by.

 

[kirk]

I've aways found that I have to reduce intensity or hrs to clear diatoms. What's that knocking sound? Is it Clive banging his head on a wall.

 

[Sacha]

Love it. I could have predicted this would happen.

Note the fact that the diatoms are only present in shaded areas, and the areas that are worst affected are the darkest parts of the tank.

 

[kirk]

I've noted the fact but I belive it's just coincidence. Are you sure it diatoms? Soon as I increase my lighting it always rears it's ugly head. it's not just in the places you miss on your routine scrap is it?

 

[Sacha]

Yes. I am sure it's diatoms.
No, it's not just in the places I miss on my routine scrape.

 

[roadmaster]

Well if it is in fact diatoms, that you reported was growing on the glass as well as lower leaves,then they are easily removed with rubbing your fingers on the leaves or wiping the glass.
Snail's ,shrimps ,otocinclus will get after em too in a hurry.
Me thinks I would do this daily or weekly if I wished for them to withdraw more quickly rather than look at it for month's.
If the area's in which the diatoms were confined to was dark as you say..then another hour of light would make next to no difference for the area's would still be dark unless you moved the light to better hit the dark area's.

 

[kirk]

Yes. I am sure it's diatoms.
No, it's not just in the places I miss on my routine scrape.

ok, only said that as you said dark places and leaves. I always miss some/ can't get to it for bog wood.

 

[sciencefiction]

Perhaps increasing the light made your plants grow faster/better, outcompeting/using up the resources the diatoms were relying upon. In my opinion diatoms are always caused by excess organics/ammonia/bio overload.
I've never caused diatoms by having lower light or fixing them by increasing the light amount. Normally on top of the diatoms green algae starts appearing when you bump up the light high. So from one algae to the other. I'd rather deal with diatoms, at least fish eat them.