brown algae(?) on glass - ID help please

[Andy Pierce]

Not really a super-big problem but a minor irritation and curiosity. I have what I'm guess is some type of brown algae which I notice mainly on glass. It might also be on hardscape but this is less of a concern. I don't see it on plants. It does not rub off casually, but can be removed relatively easily scraping with a white credit card blank (which also makes it easier to see). It is a relatively constant presence needing a good scrape every week or so. It seems to grow in more light exposed areas, but not exclusively. I have this only in my low tech glass shrimp tank. This never happens in my high tech CO2-injected acrylic fish setup.

Anyone know what this is and/or tips on prevention?

1. Size of tank in litres.
12.5L water
2. Age of the set - up.
2+ years
3. Filtration + Media/Sponges.
Sponge filter
4. Lighting and duration.
Weekaqua S400 pro. 10 hours
5. Substrate.
Sand: Hugo Kamishi quartz white sand
6. Co2 dosing or Non-dosing.
No CO2. No glutaraldehyde.
7. Fertilizers used & Ratios.
1/8 dose estimative index.
macros (weekly): K 3.3 ppm, NO3 2.0 ppm, PO4 0.9 ppm, Mg 0.7 ppm, quite a lot of sulfate as a counterion to the K and Mg.
micros (weekly): Fe 0.08 ppm, Mn 0.017 ppm, Zn 0.011 ppm, B 0.01 ppm, Cu 0.0023 ppm, Mo 0.0015 ppm
8. Water change regime and type.
80% weekly. Acid neutralised Cambridgeshire tap water. dGH 17, dKH 0.8
9. Plant list + When planted.
Submersed: Crypts, echinodorus, S repens, H quadricostatus, Java fern, Christmas moss - various timings all many months except some relatively recent Lilaeopsis novea-zelandia
Emersed: Lysimachia nummularia aurea, Riccardia chamedryfolia
Floating: Salvinia minima (always grows really well)
10. Drop Checker.
none
11. Inhabitants.
shrimp: neocaridina and caridina
snails: some type of small freshwater snail that came along for the ride with some of the plants. reasonably prolific and I don't do anything to try to stop them
12. Full tank image & Surface image.
See attached for picture of tank, algae(?) on glass and algae after being scraped. It always looks just like this.

 

[PARAGUAY]

Does that area get daylight /sunlight, complete guess diatoms attaching to biofilm, before algae develops?

 

[G H Nelson]

Looks like diatoms...... too much light and not enough surface plant cover.
Reflection from the light-colored sand doesn't help.

 

[dw1305]

Hi all,

Looks like diatoms...... too much light and not enough surface plant cover.
Reflection from the light-colored sand doesn't help.

Same for me.

cheers Darrel

 

[Andy Pierce]

Thanks all. I suspected diatoms but they (reputedly) happen more in new tanks and are a 'self-solving' issue - maybe this is less true than advertised. The tank doesn't get any sunlight but "too much light" could be investigated. An interesting piece relates to why diatoms are brown where it turns out they have an extra pigment in their chloroplasts, fucoxanthin, which absorbs green light - chlorophyll does not absorb green which is why green plants look green. You can adjust the different coloured LEDs in the Weekaqua S400 so I'm going to try turning down the green LEDs. It won't be any kind of controlled study but I'll report back impressions.

 

[dw1305]

Hi all,

but they (reputedly) happen more in new tanks and are a 'self-solving' issue - maybe this is less true than advertised.

They are, pretty much, universal in all liquid water <"Indicators: Sediment Diatoms | US EPA">. All tanks will have them present, but often in numbers too small to see (especially in established tanks).

but "too much light" could be investigated.

A lot can grow at low light levels, I'm guessing that refraction and reflection, in your white substrate, are providing the PAR they need.

cheers Darrel