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Cyanobacteria problems

A

All butter shortbread

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23 Jul 2013
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Hello,

Got this stuff covering quite alot of my substrate now and could really use some advice on killing it.

Tank is 90x30x50cm (LxWxH), with two 39w T5s, Pressurized CO2. Dosing tropica + and liquid carbon daily, plus 50/60% water changes weekly (including thorough substrate cleaning).

Also I have an external filter rated at 100lph + a newave circulation pump going at 1600lph. Judging by the movement of the plants there seems to be pretty good circulation around the tank.

Nitrates are at 25ppm, didn't bother testing for ammonia.

I've been double dosing liquid carbon to kill off black brush / hair type algae however I assume it doesn't affect this stuff..

Could someone give me some advice on what could be going wrong that causing this?

Thanks!
 
Unfortunately I do have live stock in there. Did some more reading and decided to bite the bullet and try a black out
 
I've just uncovered one of my tanks after a 3 day blackout and it really does work.
 
But if you do not change your behavior the BGA will return. Instead of testing for nitrates, you should be adding more of it. BGA almost ALWAYS occurs when the tank is LOW in nitrates. Algae never lie, but test kits do most of the time. If you are adding CO2 via gas or liquid you will always increase the demand for nitrate phosphate and everything else. You should check the contents of your fertilizer and make sure it contains NPK. If not then get NPK if it does contain NPK then it means you are not dosing enough so double or treble your dosage.

Cheers,
 
As far as i can tell the BGA occurred only in dead spots .I have since adjusted my inlet & outlets and my circulation pump and I'm pretty confident i've solved that particular problem. Concerning ferts the one I'm using does contain NPK so will up my dose

Thanks,
 
I had BGA on my substrate for months and hair algae on a few plants and just couldnt get rid of either. I used a syringe and put liquid carbon on the hair algae directly whilst in the tank for a couple of days and it was gone, but the BGA wouldnt go. One day I sat for a long time and considered things and it became obvious that the BGA was only at the front in the open spaces and not where the plants were nearer the back where the circulation is poorer and then it came to me....... i closed the curtains in the day for a few days and voila all the algae just disappeared just like that. I now douse 150% liquid carbon and Its been fine since. I am sure any experienced person would have thought about it from the start but sometimes you dont see the obvious
 
I've had a bout of BGA, for reasons I couldn't explain. Strong flow (not dead spots, I'm certain), consistent CO2, and EI dry dosing (aquariumplantfood) and still had problems. Turns out I had water flowing past bits of dead plant I had left on my tank braces. Maybe rotting plant matter is a contributing factor?
 
Plants use nitrates and phosfates is a ratio 10 : 1. So check if your Phosfates are about 2,5 !!! Also (good) light is needed. Had Cyano for several years. Swapped bulbs for 4000 Kelvin ones. Plants started to grow again, ferts were needed and Cyano was gone.
 
The rate at which plants use any nutrient has no bearing whatsoever on the ratio of nutrients that you dose. Furthermore, BGA is not correlated at all to PO4. Thirdly, PO4 test kits are not accurate, so the worst thing the OP can do is to try and measure.
The OP needs to focus on NO3 and/or flow/distribution because BGA is highly correlated to low NO3.

Cheers,
 
I'm sorry, but i totally don't get you . NO3 of 25 is low ??? I could be wrong but what i've been told / learned the last 40 years plants do use no3 and po4 in ratio 10 : 1. NO3 of 25 iis not low and shouldn't be added to my knowledge and believe. But hey I can be wrong.
 
BGA is not correlated at all to PO4
Click to expand...

That's correct with unlimited CO2,or at least an amount that is more than enough for the current plant mass but high PO4 can cause indirectly higher CO2 demand, thus causing issues with algae and even cyanobacteria.
And on another hand,the more the PO4, the more the demand for NO3 as well. So I think it can be very much related depending on the type of tank one has.

I agree in unlimited tank that's not an issue but theoretically if you take a different approach you can lower the PO4, which will indirectly lower demand for NO3 and CO2, thus balancing the tank, taking care not to cause PO4 related algae like greenspot at the same time.
And the alternative option is to follow the EI method, and increase NO3 and sort out the flow and CO2 instead,
 
DoubleDutch said:
I'm sorry, but i totally don't get you . NO3 of 25 is low ??? I could be wrong but what i've been told / learned the last 40 years plants do use no3 and po4 in ratio 10 : 1. NO3 of 25 iis not low and shouldn't be added to my knowledge and believe. But hey I can be wrong.
Click to expand...
Well there is a simple explanation. Nitrate test kits are incapable of accurately measuring NO3. As I mentioned, algae are totally aware of what's happening in the tank and test kits are not, so the appearance of BGA, which is triggered ONLY ever by poor NO3 tells you immediately that the test kit is incorrect.

Plants use NO3 and PO4 at whatever rate they need, depending on the environmental conditions, depending on what species they are, depending on their state of health and depending on the light intensity as well as a host of other conditions, like CO2 concentration. The ratio is a rough guide based on the molar content of these compounds within the tissue, but it should never be used in a dosing program because you cannot control where, or at what rate the PO4 or NO3 enters the plant. There is uptake from leaves as well as from root, so there is no way your dosing can ever be controlled. The better strategy is to dose unlimited amounts relative to the plant's needs and to allow the plant to decide how much and how fast the uptake will occur. Managing nutrient ratios is a very poor way to dose. I ignore all ratios and yet do not suffer any deficiency issues...at all.

Here is an example of a tank dose at a NO3/PO4 ratio of 2:1
In nutrient dosing, one only ever needs to worry about avoiding falling BELOW the minimum nutrient concentration threshold.
One NEVER needs to worry about ratios.
8394115845_d7ca6ffd66_c.jpg



sciencefiction said:
That's correct with unlimited CO2,or at least an amount that is more than enough for the current plant mass but high PO4 can cause indirectly higher CO2 demand, thus causing issues with algae and even cyanobacteria.
Click to expand...
There are many indirect contributing factors, but this is not a logical troubleshooting path at all. When you see BGA, fix your NO3, full stop. Analyze the reasons for the low NO3 and fix this direct causes FIRST. It makes no sense to address indirect contributing factors until you have assured yourself that the direct causes are fixed.

In this case, the OP has not really addressed the direct cause. He is using a low dosage fertilizer (one that is mostly water) and is relying on a proven false indicator, therefore the best course of action is to add more NO3 first. PO4 is far down the line and is tertiary indirect contributing factor at best.

Cheers,
 
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Ok, but there has to be (any) PO4? Is there in this tank? Nice pic / tank by the way. Still understand the NO3 of 25 to be (too) low.
 
As I repeatedly mention, the test kit readings cannot be relied upon. The appearance of BGA indicates with much greater accuracy that the NO3 concentration is much closer to 2.5 than to 25. If you continue to trust test kit readings you will continually be chasing your tail.

The amount of PO4 added to this tank was 10- 20 ppm plus whatever was in the tap water.
Yes you absolutely need PO4. PO4 should be dosed at unlimited levels and NO3 should also be dosed at unlimited levels. Where your ratio comes in is the fact that plants do use a lot more NO3 than PO4. So the amount required for an unlimited quantity of these two is different. This is true due to the fact that PO4 is a recyclable product to some extent because it is used in cyclic energy transfer for many chemical reactions. Phosphorous is a high energy element and is in very short supply naturally, so plants and animals have discovered how to survive with much smaller amounts. By contrast, Nitrogen and it's compounds are ubiquitous, so the consumption and the way in which N is used causes the demand for this element to be much higher. Nitrogen is the second most important element to plants, while Phosphorous is a distant third.

Cheers,
 
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Thanks for the explanation. I meand the PO4 in the tank of the OP. If testkits won't work, how can you test that. Or should OP simply add that as well?
 
Oh, sorry, I misunderstood your question. The answer is "yes absolutely" he should add as much of NO3/PO4/Trace elements as he can. That is one of the reasons people have difficulties in planted tanks. They take reading from useless test kits and of course, the test kit returns a high reading, so they trust the readings and assume they have plenty of whatever compound they are testing for - while all the time, the real nutrient level is actually low. Then they assume that it's because the nutrient concentrations are high that they have problems, never realizing that the tank is suffering severe nutrient shortfalls.

Whenever you see an algal bloom, it usually tells you that some nutrient concentration level is acutely low.

Cheers,
 
Took your advice - increased fertliser dosage from 2ml to 5ml. All traces of Cyano (and some black brush algae) have dissapeared from the tank after the black out so hopefully it won't come back.

ceg4048 said:
They take reading from useless test kits
Click to expand...

You seem to be the expert around here so I'll take your word for it, so without test kits how do you keep track of nitrates with sensitive fish? I plan on getting some mikrogeophagus ramirezi when the scape fills in and apparently they don't like nitrates above 20 ppm?
 
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