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Green dust algae on day 6 of dosing every week?!

Sacha

Member
Joined
3 Jan 2014
Messages
992
Location
London
I have been having this issue for the last few months, and it is the only issue I currently have in my tank with algae.

I follow the following EI dosing regime:

Monday: Micro
Tuesday: Macro
Wednesday: Micro
Thursday: Macro
Friday: Micro
Saturday: Macro
Sunday: Water change, then Macro

Monday- Saturday are dosed in the morning before lights come on. Sunday is dosed in the evening after the water change.

You are not meant to dose on saturday, you're meant to have a day off. The reason I dose on saturday, is because I spent months having a rest day, and that would mean that on saturday/ sunday I would get an outbreak of green spot algae/ green dust algae. I started testing my phosphates and nitrates, and both appeared to be hitting zero around friday/ saturday. I don't want my nitrates or phosphates to ever hit zero, so that's why I am dosing on saturday.

The issue I have now, is that every saturday or sunday I get an outbreak of green dust algae on the glass of the tank. It is easily removed with an old credit card, but it is a nuisance and I want to find out what's causing it.

The fact that it only appears towards the end of the week implies that it is a nutrients issue, as opposed to light or Co2.

So, what nutrient imbalances cause green dust algae, and how can I combat it?

Thanks.
 
Hi Sacha, funny to hear that you only get them on Saturdays. I have the same regime, but I basically get GDA everyday! I have been scraping them for a year now, and I am thinking how others are able to achieve a clean tank without it. Do you basically get a clean tank without any GDA at all on non-Saturdays?
 
You don't state tank size and by how much you are over lighting it...oh bum clue in last sentence..
 
Tank is 125 litres.
Lighting from 2 T5s. Arcadia Plant Pro 25 W tubes. Lights on from 11:30- 22.30 daily.
 
That's 33 US gallons @ 50W -> 1.5W/USg so heading into high tech. And having light on for 11 hours !!!! You are killing your plants with too much light and not enough nutrients and/or CO2, which is why the algae is winning. Plants are probably dying and releasing waste into the water feeding the algae.

Try initially just one tube for significantly less hours maybe 6 hours and see what happens.

When I high tech'ed my 180l with 50W T8 tubes, I ran for 6 hours a day, with both tubes partially blocked by rotating the reflectors round. No algae at all. After couple of weeks and plants had settled in, rotated reflectors round and increased lighting to 9 hours, again no algae.
 
The plants are doing great, they are not dying. I have a huge amount of co2 and ferts which can keep up with the high amount of light. I started with 8 hour photoperiod and increased it gradually. If you have enough co2 and ferts, you can actually go up to a 14 hour photoperiod before the plants start suffering.
But I will turn my light down by one hour and see if it helps, thank you.
 
If you add some bushy nose plecos, they will take care of things. Maybe 4-5 babies in a 100 liter tank should do the trick.

8 hours for the lights.
 
Thanks :)

I am not a fan of adding fish just to combat an algae problem. I perfect to identify the root cause of the problem, and eliminate that, rather than just treat the symptoms.

I have turned my lighting down to 9 hours. I will gradually further reduce this to 8 hours.
 
I still have this problem.

The lighting is not the cause. It is something to do with the nutrients.

From Monday all the way until Friday morning, there is no dust algae. On Friday evening, I have dust algae.

This is clearly something to do with the build- up of nutrients over the course of the week. If it were a lighting issue, it would not happen in such a regular and predictable way.

Does anyone have any advice?
 
Ok, thanks Ian.

The thing is, I would think the tank is 'settled' by now. It has been running with this level of stock, this level of ferts, this level of co2, for over a year now. If this problem were going to sort itself out, I think it would have done so by now.

I see that some people recommend having one rest day (Saturday), and some people recommend having two (Friday and Saturday).

I currently dose Micro on monday, Wednesday, Friday. Could it be the Friday dose that is causing problems?
 
I can't see how it would appear and disappear that quickly, seems very strange to me, something I've never seen.
 
It doesn't disappear. I scrape it off every Sunday right before the 50% water change.
 
Is it not that it takes the week for the algae to build up to a significant enough amount that can be seen on the glass?
 
The glass is literally spotless from monday- thursday. Not a speck of algae.

Then friday afternoon... bam.
 
Dude go read up on some of Clive's replies regarding any algae issues.

Too much light does cause algae, you will see nobody runs their light for 11 hours mostly between 6-8 hours.
 
My lights have been running for 8 hours now for about 6 weeks and I still get this problem every Saturday. I highly doubt that it's light related since the glass is spotless Monday- Friday.
 
56W of light in 125 Litres.

I'm grateful for your help, but light is not the problem. How would that explain it appearing on Friday afternoon/ Saturday morning every single week like clockwork?

The only thing that can explain that is a nutrient cycle
 
Nice, do yourself a favor send Clive a pm regarding this and I am sure that he will be able to help you out.

One thing you can try out is start dosing macros in the morning and micro in the evenings, it could be that by Friday evening you dont have enough ferts in your tank and this is why algae pops up.
 
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