Can Cold Cathodes Encourage Algae?

[xing]

hi all

i fitted some blue cold cathodes recently for a moonlight effect and have noticed an increase in algae generally. Whereas previously I "only" had BBA which I cleared with flouish excel (and it didn't return), I've now got what looks like staghorn (softer, longer and paler green than the BBA) and a longer filamentous (sp?) algae (hair algae?). the Excel doesn't appear to be working on this and I'm wondering whether it could be the moonlight - can't see why but I'm stuck for any other solution as nothing else has really changed. Tank is pretty standard with approx 1.75wpg plus DIY CO2. Dosing excel flourish daily as per instructions plus adding KNO3 to 5ppm 2-3 times weekly (although I've cut this back as I thought it may be a cause). was changing 30% weekly when all ok, but have moved to 25% x2 per week since the probs to see if it helps. All readings showing ok

NO2 - nil
NO3 - 25ppm-50ppm
PH - 6.8
kh - 3
co2 therefore 15ppm? not optimal but on DIY hence adding excel

Can anyone offer any advice as its looking like I'll have to ripp out a load of pretty badly affected plants that are either covered or now struggling

 

[BNyleen581]

Hey Xing,

When I was living in Georgia a guy there did the same thing, using blue cold cathodes as a night light and guess what? He had the same problem.

Upon researching (just a little) cathodes regardless of color often peak at several different areas of the spectrum that algae like. They don't peak a lot, but enough to feed those little algae spores so they can settle down and make a home of your tank. Between that and your day light those algae are probably very happy.

I would suggest you switch to LED lights. I have a few in my tank and they look really good and the frequency of light is so negligent that I don't think it's possible for anything to grow.

Good luck.