Green Dust Algae

[o2bubble]

Hi all, I noticed I have some green dust algae on my tank glass. Not sure whats the cause and need some suggestion..

This is my tank parameters:

Size: 4x1.5x2 ft (about 300l)
Lights: 2x150w MH, 7 hours/day (About 3.3 w/g)
CO2: ard 30 ppm as confirmed with drop checker using kh 4 solution
Substrate: ADA powersand/Amazonia
Fertiliser: Dosing 3x a week: 15 ml ADA brighty special lights, 30 ml ADA brighty K, 4 ml ADA Green Gain, 5 ml ADA ECA (about 90 drops). Every 2 weeks: 30 ml Dennerle S7 (vitamins)
Temp: 25c

I took some measurement last weekend:

KH: 3
PH: 6 - 6.2
Nitrate: 15 ppm (with tetratest nitrate test kit)
Phosphate: 0.5 ppm (with Aquarium pharm test kit)
Ammonia/Nitrite: 0 ppm

Plants are growing fast and shows no other signs of nutrients deficiency except some signs that iron is not enough, R. indica/ludgwia/tellenus redness seem lacking. That's why I uped ECA dosing from 2 ml to 5 ml.

Could it be my N and P is not enough while iron is in excess? should I up Brighty special lights to 20 or 25 ml? Btw, I started using special lights 2 weeks ago and notice that with the additional P in it, my green spot algae reduced much.

[zenscape]

MH may be too strong for the size of your tank. I am not sure but it is relative to plant mass, parameter of fert and biomass.

Increase your N&P. Your test kits may not be accurate and there's the reason of using EI method to ensure all things are sufficient.

A sign of little GDA spells bad news as it will aggravate to a point when your tank surface is green just after WC a day or two.

There are two ways to get rid of GDA:-

1. Wait till it finishes its cycle and it will get harden. Just scrap it off.

2. Attack it with brute force.

Option (1) is only viable if you can wait. But it seems that no one would want to go home to a green water box, in particularly, CNY is around the corner.

Option (2), I learnt it from Tom Barr and had tried that before and it works-

Scrap the surface clean and do a large WC (90%). Refill the water and WC another 90%. Next day do the same. 3rd day do the same. Get back your Co2, NPK and trace up and good. Plant more.

Modified method:- Don't wipe GDA out first when water is in the tank but first pump out water until 2 inch from sand. Then use tissue or dry cloth to wipe the surface clean. Same procedure as above such as large WC for 3 days.

Try this and hope that your GDA is gone before CNY.

[o2bubble]

Thanks bro... I'm just leaving it and waiting as I'm too lazy to clean the glass Anyway, only a small portion of 1 side kenna GDA and I have increased the dosage of my Special lights fert. I suspect that ADA special lights must be used in complement to ADA step fert as well since special lights contains lesser trace elements and mainly NPK and I will be using Step 2 to see if I can improve the situation.

BTW, I had start on MH since Nov and only recently 2 weeks ago, the GDA starts to appear. Previously when using only ADA Step 2, there is only GSA but after I started on Special lights, GSA reduce but GDA appears. Maybe also, recently I tried to lower my CO2 due to drop checker indicating yellow with my tank water (found out must use KH 4 instead) and then increased back later..

[o2bubble]

Almost gone after reduce fert dosage, changed water and cleaned the glass Will do another water change and cleaning after 3 days.