Brown Algae

[RYO]

keep getting this poxy algae

tank stats
60L planted tank + (2x 36w T5 power compacts (6500 k) +reflectors)1x nutrafin co2 unit
Filtration- Eheim 2231 (poxy filter, don't buy 1)added fluval 2+
ph -6.4
ammonia- 0
nitrite -0
nitrate - 15 ppm
phosphate - 1.5 ppm
gh- 2 deg
kh- 3 deg
temp 27c

Most site state that brown algae (if it is this stuff) is caused by lack of light, well at 6 wpg i think i can rule that one out.
If any one has a solution I'm all ears

 

[zig]

I Dont really know other than reduce the lighting to 1x36 watt, your Gh is also quite low, under 3 usually signifies that you will be low in calcuim or magnesium (usually magnesium) my Gh is 3 but i got a water report for my area and i have a magnesium deficiency so i dose epsom salts once a week at water change, your mg readings should be around 5-10ppm mine from the water report were 1.5ppm, there is no way to test magnesium easily, people will usually test for calcuim, you want a ratio of about 4 to 1 calcuim to magnesium, it might be worth your while ringing your local water company and getting a water report to find out for sure.

But i think its probably more to do with the light, if you were able to reduce the lighting even for most of the photoperiod and then give it the full blast of the 6+ WPG for part of it (maybe 3 hours or even 2 hours) this would probably do the trick, but it would probably work just as well to use only the 36 watts for the full photoperiod.

Other than that im not really sure, but my best guess would be the light, although the mg could be a factor as well especially at the level of light you are using.

 

[RYO]

Doh !! that is a prob , its a twin t5 fitting from 1 controller.
I'll try the water company see if they can shed any light.