How to fight Green Dust Algae?

[saugata]

Hi! All,

I am having a 90g planted tank and its about 8 months old. As with any new tank setup I also had my share of algae but one by one all came and went off. The only thing which is really hounding me is the GDA on the glass walls. I have tried letting it be there for a month or so and then scrape the walls with regular w/c (the day of the scraping, 2 back to back w/c, followed by two 60%w/c on the next 2 days). I hope this time I will be able to get rid of them but then I am not sure. Last time it did come back. Now what's the cause of this & how can I get rid of them?

My dosing schedule:-

* Lights - 36watts x 5 nos of Philips T8 (6500K) + 36watts x 3 nos of Osram 8000 K T8 lights @ 12 hrs/day with a siesta of 2 hrs from 2pm to 4 pm

* Ferts: On the day of w/c - 20 mls of KNO3 (stock sol. of 8 tb spoons in 400 mls of Distillld water), 4 mls of KH2PO4 (stock sol. of 2 tb spoons in 400 mls of distilled water, 4 mls of Trace elements).
on the 4th days 20 msl of KNO3, 4 mls of KH2PO4 & 4 mls of Traces

* CO2 - Pressurised - atabt 30 PPM

I hope someone will be able to help me with this as I don't want to live life-long with the GDA.


Regards,

Saugata

[benny]

Are you refering to Green Algae? Not quite sure what does GDA stands for...

Cheers,

[PeterGwee]

Consider a running a UVC after cleaning the glass and add more current especially to the front of the tank. You are running things way too lean for the plants and that is not good. They slow down in growth and that is always a leg up for the algae.

Regards,
Peter Gwee

[saugata]

Hi!

@ Benny - GDA - Green Dust Algae

@ PeterGwee - "You are running things way too lean for the plants and that is not good." - Can you please elaborate on this? I am not being able to figure out as to what exactly you mean by this. I tried increaseng the current and had installed an additional powerhead for increased water circulation and the water current was aimed towards the front glass wall but no results.

Regarding the growth of plants, I have to do a major trimming once every 20 days as my tank will become a jungle.

[eddyq]

I would also sugguest install and run an ultraviolet light to combat GDA. In my opinion, lean dosing and strong lighting encourage algae.

[saugata]

Hi!,

I have been trying to tackle GDA for the last 2 months but I think I must be doing something wrong as its coming every time.

Last time what I did was do a 75% w/c (i.e. on last Saturday) after letting them grow for about 1 month and then did back to back w/c after scraping them off. Post this I did 70% w/c on the next two days i.e., on last Sunday & Monday but unfortunately I can see the damn thing coming back by yesterday night.

How do you manage to keep the GDA from falling off into the water while you are scraping them off? Moreover what about the GDA which is there below the water line? I have quite a no. of fishes and hence can't drain out the water completely. Max that I could go to is about 70%.

I have now reduced the light level to 10 hrs from 12 hrs with a siesta of 3 hrs in between. In fact what I am planning to do is have the following lighting arrangements:-

8 AM to 12 Noon - T8 @ 36watts x 2 nos
12 Noon to 3 PM - T8 @ 36 watts x 8 nos
3 PM to 5 PM - all lights off
5 PM to 8 PM - T8 @ 36 watts x 8 nos
8 PM to 10 PM - T8 @ 36watts x 2 nos

OR

10 AM to 2 PM - T8 @ 36 watts x 8 nos
2 PM to 6 PM - Siesta i.e. lights off
6 PM to 10 PM - T8 @ 36 watts x 8 nos


Which one do you think will help the most? As I understand excess light is also responsible for GDA.
Generally I am at home till 8.30 AM in the morning & after 7PM in the evening so would like the tank to be lighted so that I can enjoy the view.

By the way, my fert dosing schedule is as follows:-
On the day of w/c - 20 mls of KNO3 (stock sol. of 8 tb spoons in 400 mls of Distillled water), 6 mls of KH2PO4 (stock sol. of 2 tb spoons in 400 mls of distilled water, 6 mls of Trace elements). on the 4th days 20 mls of KNO3, 6 mls of KH2PO4 & 6 mls of Traces. My tank size is 90g and is densely planted.

Is this ok or I need to tweek it around a bit?

Eagerly looking forward to inputs from experts.

[FC]

Saugata,

GDA is greatly promoted with light hours more than 8 hrs.

To totally get rid of GDA, go and get a UV canister light, this is the best bet you can have. Get the one with 13 watts or more.

[neon]

I followed one of the suggestion(believe is Tom Barr), leave it alone until harden. Prepare to leave it on the glass for at least a month, until don't see any new visible sign of new GDA (tiny & green) from front and the side.