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GSA on anubias and PO4 dosing

A

Ajm200

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19 Feb 2010
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534
Location
London
Got a few spots of GSA on the remaining anubias in my 500l tank. It is the only sign of algae so far.
I seem to remember reading on here somewhere that upping PO4 can help clear it.. Did I imagine it?

Currently dose

(2tsp KN03 + 1tsp KH2PO) X3/wk
(1tsp trace + 1tsp Epsom salts) x2/wk

With pressurised CO2

What do you suggest?

Thanks
Amanda
 
Ajm200 said:
Got a few spots of GSA on the remaining anubias in my 500l tank. It is the only sign of algae so far.
I seem to remember reading on here somewhere that upping PO4 can help clear it.. Did I imagine it?

Currently dose

(2tsp KN03 + 1tsp KH2PO) X3/wk
(1tsp trace + 1tsp Epsom salts) x2/wk

With pressurised CO2

What do you suggest?

Thanks
Amanda
Click to expand...
Hi Amanda,
Green Spot Algae (GSA) is linked to deficiency of either PO4 and/or CO2 (of course flow/distribution as well). The problem is that it's difficult to determine exactly which, so you have to look at other clues in the tank. If you see other indication of poor CO2 for example, such as hair or browning or other structural problems, and if you don't see GSA on other plants then it tells you that the culprit is most likely CO2/flow. If you do not see any indication of either, i.e. if the tank is otherwise clear then you are in the category of Anubias and it's slow growth. Instead of adding more nutrients/CO2/flow, if Anubias is the only sufferer thentry relocating it so that it's shaded. If you don't want to do that then simply trim the affected leaves and allow the plant to grow new leaves, which it will. Anubias is particularly susceptible to GSA as a result of it's slower than normal growth rate.

If there is GSA on other plants then you must conclude that the deficiency is pandemic, therefore you can double the PO4 and take a reading after a few weeks. 500L is a large size with inherent inefficiencies associated with nutrient and CO2 delivery.

It's easy for me to say "add more nutrients", but doing this adds more growth and therefore adds more requirement for cleaning/maintenance. If the GSA is specific to the Anubias then it might be as easy to simply lop off their heads and carry on.

Cheers,
 
I've followed your advice added a third filter, moved the co2 timer forward to maximise co2 at lights on and adjusted the spraybars to maximise flow so I hope it isn't co2/flow related. Can't increase the amount of co2 going in without risking CO2 toxicity.

Been thinking about it and the GSA did appear after we had the lights on much longer than usual for two consecutive nights (for maintenance and while guests were here.). I think I'll shift everything back a few hours so that the tank is lit much later in the day to stop these extended photoperiods

The anubias is in line with the spraybar that releases co2 into the tank and the upper spraybars keep the bubbles down well so that the tank is misty with bubbles so think I can rule co2/flow out for now. It isn't shaded so maybe it's getting too much light especially in the past week. Also, the tank is still new plus I added a few more fish last weekend so there may be a bit of ammonia around to encourage the algae.

I'll start with

1 less light (no more extended photoperiods)
2 more water changes to remove any ammonia from the extra fish
3 Replace the eheim air stone with a glass difusser when it arrives from HK to reduce CO2 bubble size going into the filter. The co2 does collect in the spraybar over time. Micro bubbles going into the filter might help more of it dissolve.
 
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