ehiem substrate leaching silica/diatoms, freshwater

[astroboy]

Hello,

 

I have a 90 gallon freshwater tank, running CO2, lots of lighting, packed with Amazon swords and a few vals. Been set up for six months now. I've had very little algae at all. For a freshwater tank, the fish population is at most moderate. 

 

In the last couple of weeks I've had a fair amount of diatoms (brown algae) and the plants aren't looking so good, I think because the diatoms on the leaves are blocking just enough light to do harm.

 

In my wet/dry filter I have a layer of Eheim Ehfisubstat biosphere: sintered quartz. I'm wondering if 

 

1) it's possible that the balls are leaching silica into the tank, which diatoms love, or 

2) there's something else favoring diatoms or perhaps some kind of genuine brown algae since I haven't rinsed off the balls since I set up the tank.

 

Any thoughts, especially on No. 1?

 

Thanks,

 

Mark

Edited March 28, 2017 by astroboy

[freshfins]

Diatom outbreaks are typical of a new setup. You just wait it out and the silica gets used up and the diatoms go away. It can also be caused by old light bulbs that have shifted out of spectrum. Check out this article:

 

http://gwapa.org/wordpress/articles/algae-in-the-planted-aquarium/#diatoms

[astroboy]

Diatom outbreaks are typical of a new setup. You just wait it out and the silica gets used up and the diatoms go away. It can also be caused by old light bulbs that have shifted out of spectrum. Check out this article:

 

http://gwapa.org/wordpress/articles/algae-in-the-planted-aquarium/#diatoms

 

Thanks very much for the info, but  the bulbs are just a few months old and are LEDs, so I don't think 'decay' is a factor.  Although, I had been using compact fluorescents up until 4-5 months ago. I would have thought the change in lighting would have had a more immediate effect... Just from eyeballing, I'd say the brightness is pretty close and it worked well in the past. 

 

The gravel was in the tank for three years, very low fish population, I rinsed it all out when I moved six months ago, which I'm sure killed a lot of good bacteria, but for the first couple of months I had a very low fish population with that in mind. This diatom thing is rather low grade but it happened only within the last few weeks, more or less literally overnight. I'm pretty sure none of my kids dumped a handful of fish food in the tank.....

 

I'm wondering if the substrat balls aren't the problem. Five or six years ago I had them in my saltwater tank but after reading alot of WAMAS posts I decided that likely they were just nitrate sinks, at least in a saltwater tank. To clean them off I put them in CLR and they dissolved like sugar in water, almost..... Big surprise. I would have though they were inert, being glass, as I understand it. That didn't stop me from buying a new batch for the freshwater tank. My big question: I wonder if at some point once enough organic matter accumulates in/on glass balls they don't start to slowly dissolve, something like tooth decay. Bacteria forming an acid film on the surface, something like that .