stuborn algae

[stef25]

i have a serious green algae problem with a tank ive had for three years now. the algae have always been there from the start and no matter what i try (chemicals, algae eaters, rebuilding the tank, adding more plants, ...), they dont go away.

they first appear on the glass, and then move to the rocks, discoloring them completely. they destroy any plants i put in there. the tank is properly cycled and although its maybe a bit over stocked, i manage to keep the nitrate levels relatively low with water changes. only one fish out of 12 has died over the years, so i think the quality of the water is not that bad

the tank is of the "Jewel" brand and came fully equipped. i realise now its a bit of a "beginner/kids" tank and that the filter or pump may just be crap.

i have ceramic tubes as media, with an active carbon sponge and a layer of cotton wool type material - this should be sufficient, right?

could a bad pump/filter be the reason why i have this problem? or should i look at other factors first?

im willing to try anything to solve this algae problem (money no object) and would like to get a serious external filter. i really love the tank, the fish and spending time working on it. it's just so demotivating that every time i think "now ill have fixed it" the algae appear again within days, as im sure you all understand!

thanks for any advise

 

[FishGeek]

How long during the day do you leave the lights on?? Is there any way sunlight is hitting it??

 

[stef25]

ive brought it down to 8hrs a day. yes, sunlight was hitting it (its v close to a lg window) but ive been closing the curtains for a few weeks and it doesnt make much of a difference. should i get darke curtains or try to cover the tank with a blanket to see if it makes a difference?

 

[FishGeek]

Is there another place to put the tank. That is probably your culprit. I think that have the curtains open before has caused it to grow. And now you have it and so even keeping the light on for a period of time is giving it the light source that it needs.

 

[Lotus]

Do you know what kind of algae it is? Is it hard green spots, or more like a slimey sheet-type algae?

 

[stef25]

slimey sheet type. it makes a film on the inside of the glass.

So, ill move them to a dark corner but will first re build them. how should i disinfect the tanks so that all traces of algae are gone? just wiping the glass doesnt do the trick ...

 

[Lotus]

The problem is that you have blue-green algae, which is a cyanobacteria, a cross between a bacteria and algae. Consistenly low nitrates can cause it, and poor water circulation can help it, too.

To get rid of it, you can either do a 5-day blackout of the tank, or use erythromycin. Erythromycin is an antibiotic available in fish stores, but it can disrupt your biological filter.

To do a blackout, you will need to
- Do a large water change, remove as much of the stuff as you can
- cover the tank completely so no light can get in
- do not feed and do not peak for 5 days
- after 5 days, take off the covers and do another large water change.

 

[cybersymes]

i think light must be your problem...
[you know this already...]...

my tank is a 'juwel'...pumps and filters are fine...
lots of water movement...no algae...

i wasn't aware that i might have a 'kids tank'...
i'm going off into a [dark] corner to huff ...

 

[stef25]

Thanks for this explanation.

did i read that right - consistently LOW nitrate levels cause cyanobacteria to flourish?

Regardless of the algae problem, I will be rebuilding the whole tank. The room is being redecorated and the tank needs to be moved. Big job, but it has to happen

Would it be best to empty water, gravel, scrub the tank and soak it in triple strength erythromycin concentration for a few days while covered with a blanket? The fish will be safe in a temporary new home. or do they need the treatment too?

Will the good bugs on the filter medium and plants survive an antibiotic treatment?

maybe the jewel tanks are fine, you probably know better than i do

 

[Lotus]

Yes, low (or zero) nitrates for several weeks can cause cyanobacteria to flourish.

To be honest, I would move the tank, set it up again, then treat. You need to be able to monitor that the fish are OK with the move before you go blasting the tank with antibiotics. Actually, I'm guessing you're in the UK, in which case it will be hard for you to get hold of antibiotics anyway. If you do the blackout, wait at least a week after you have set up the tank again to make sure the biofilter is working fine. If you have to do a blackout, you need to make sure the tank is otherwise stable first.

Basically, anything from the tank could transfer the cyanobacteria (water, gravel, tank itself, fish), so you will need to make sure you get rid of it by treating everything.

IME, deal with one thing at a time when it comes to your tank. If something goes wrong, you will know it could only be due to one thing.