# Blue-green algae and plant nutrients



## ifb-online (May 15, 2006)

Warning - long post!

Hi, it's been a while since I first posted when my tank was just a couple of weeks old - at least two months, so a lot of water has been through the tank since then!

Have been having some problems with blue-green algae and I need to know a bit more about feeding the plants, indeed there may be a relationship between the two.

To recap: 120 litre (26 imp.gal., 32 US gal.) low and wide tank (18 (hieight)x12x40 inches). I added a second light and now have one 30W daylight (green-ish white) and one 30W Trident triphosphor (pink-ish) light. I have also added a Hagen CO2 (secondhand bargain!) system. The water's pH was in the region of 8 (I have very hard water here - GH and KH in the teens) but the CO2 has pushed that down to 7.5. I now have a second s/h Hagen kit - wondering if I should employ both, but that is another discussion topic.

Plants: two Amazon swords and a variety with rounder leaves, some crypts, Vallis, some Cabomba and Limnophila Heterophylla (stem plants), some Java fern and, finally, some Lysimachia nummularia 'Aurea'. The substrate is plain gravel; 3-4mm pebbles. 

Fish: 7 Danios of various types, 6 Corys of various types, 3 Dward Gouramis, one albino Ancistrus bristlenose Pleco and there are also a couple of Amano shrimp in there.

The Ancistrus solved an earlier problem I had with brown algae - clever fish!

The Lysimachia and Vallis seem prone to hosting blue-green and hair algae and nothing seems to want to eat either. I forgot, there is now a healthy colony (infestation?!) of snails.

More worrying, the blue-green algae has been carpeting the gravel, though I hoover this up as best I can weekly during the water change.

The stem plants have been growing vigorously, though I suspect all is not well as when I have been forced to cut it back the gaps in the stems are very long. The green colour is not as vibrant as I would have expected, either. The Vallis seems to be growing well and has spread widely and I have chopped a fair bit out recently.

I geat a reasonable amount of pearling, though this only starts a few hours after the lights come on. The photoperiod is 8AM to 9PM.

Nutrients: I add Nutrafin Plant Gro - which is basically chelated iron and trace elements, as directed, once a week, but nothing else. The tap water has 10-20mg/litre NO3 anyway and whenever I test the tank water it appears to be the same as the tap water, though the Hagen test kit I have for NO3 is very difficult to read.

So the question is (finally!) what's missing? - am I doing anything wrong and how can I get the blue-green and hair algae under control? Googling around, I hear that low nitrates, too much iron and high temperatures (the tank has been averaging 82-83F during the day during our warm summer) could be a cause. It has also been suggested that I don't vac the substrate or reduce to a minimum.

Any suggestions welcome!

Ian


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## Bert H (Mar 2, 2004)

Hey Ian, low nitrates is a typical cause of bga. But if I understand your post correctly, you say your tap has 10-20ppm NO3 to start with. Is that value obtained via your 'hard to read' test kit or from your water source's information? If you're using the test kit, make sure you calibrate it with a known concentration solution. Test kits are notoriously wrong.

If you do indeed have NO3 in the 10-20 ppm range, let's go on to the next possibilities. You don't mention dosing any macros (these are NO3, PO4, K). These should be in the following ranges: NO3: 10-20ppm; PO4 1-3ppm; K 10-20ppm. The plant gro you're dosing is basically a micro mix, keep adding that. Check out the sticky hereto get some idea of a dosing regimen. Once you decide on the regimen, stick with it. Consistency is of utmost importance in keeping algae at bay. Give the plants all they need consistently, success will follow. In the meantime, do a thorough cleaning of all the plants, gravel, equipment, and a major water change. Then start the dosing regimen you decide on. Good luck.


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## ifb-online (May 15, 2006)

Hi Bert,

I do keep any eye out for aquarium plant food products in the local shops, but only ever see the 'micro mix' types. Is there anything more generic I can use, or do you recommend any brands and suppliers? I'm in the UK, but maybe I can find equivalents here if you can provide some examples.

Ian


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## werner (Jul 6, 2006)

I had a bad outbreak of cyanobacteria (BGA) recently, though mine was black. Try to manually remove as much as you can from plants, gravel, etc., and vacuum up any bits that float to the bottom. Reducing your light is helpful; cut down your photoperiod by a few hours (this will also help your stem plants to grow more compactly) and/or do a 3-4 day total blackout (tank covered). If you see any little spots coming back, you can zap them with a bit of hydrogen peroxide in a syringe- don't go nuts with this since it can harm your fish in larger doses. If all else fails, you can nuke it with antibiotics (it's a bacteria, not an algae). Of course, this will totally mess with your beneficial bacterial colonies too, so I would consider this as an absolute last resort.


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## hoppycalif (Apr 7, 2005)

Before anything else, get the fertilizing routine set up to provide adequate nitrates, phosphates, potassium and traces and CO2, as Bert recommended. You can use some brands of stump remover for nitrate - they are potassium nitrate, or you can get potassium nitrate (KNO3) from hydroponics stores, from Greg Watson, or, so I hear, from pharmacies. You can use some types of enema for phosphates, but make sure that's the main ingredient and there is no mineral oil in them. Flourish or other trace mixtures are ok for traces. And, either Flourish Excel for carbon, or pressurized or DIY CO2 for CO2. Once that is done, forget the test kits and just do the EI method of fertilizing at least until you can get an algae free tank going. Only then should you start trying to finesse the fertilizers.


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## ifb-online (May 15, 2006)

Antibiotics are not available over the counter in any form here in the UK - only through prescription. I'd want to avoid that route anyway.

I did a clean and prune the other day and so far the stuff hasn't come back as fast as it has done in the past.

But I'm still keen to know more about making the main plants grow better as this could help them out-compete the BGA (lots of documented experience supports this).

Ian


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## Laith (Sep 4, 2004)

Dry chemicals in the UK can be found here:

http://www.aquaessentials.co.uk/index.php?main_page=index&cPath=145_146

And calibrate that test kit to make sure you do have NO3 in the water. I've seen NO3 kits measure 30mg/l of NO3 in distilled water!


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## wiste (Feb 10, 2006)

A 13 hour photoperiod seems a bit long.


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## ifb-online (May 15, 2006)

Really? I'm pretty certain that sunlight can shine for up to 13 hours in the tropics. It was originally 15 hours, but I reduced to 13.

Ian


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## ifb-online (May 15, 2006)

I'm not banking on the accuracy of my test kits, but one thing is pretty clear and that is that my tap water has more nitrate in it than than the tank, suggesting that the plants are soaking up more nitrate than the tank's nitrifying bacteria can produce (and the tank is cycled). 

Ian


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## ifb-online (May 15, 2006)

Laith said:


> Dry chemicals in the UK can be found here:
> 
> http://www.aquaessentials.co.uk/index.php?main_page=index&cPath=145_146
> 
> And calibrate that test kit to make sure you do have NO3 in the water. I've seen NO3 kits measure 30mg/l of NO3 in distilled water!


I might be able to get crystaline KNO3 from my pharmacist - what is the formula for dilution to a known concentration?

Ian


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## hoppycalif (Apr 7, 2005)

ifb-online said:


> I might be able to get crystaline KNO3 from my pharmacist - what is the formula for dilution to a known concentration?
> 
> Ian


Here is a good website for figuring out the answer: http://www.csd.net/~cgadd/aqua/art_plant_dosage_calc.htm


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## ifb-online (May 15, 2006)

Thanks Hoppy.

Have since come across Seachem Flourish varities including Nitrogen, Potassium and Phosphorous. I expect these would work out more expensivethan buying the dry chemicals and mixing up yourself, but apart from that are these products suitable for the application being discussed?

Ian


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## Laith (Sep 4, 2004)

Yes they are.


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## hoppycalif (Apr 7, 2005)

It is my impression that, unlike some aquatic plant suppliers, Seachem can be trusted completely to produce good fertilizers and other chemicals. I would have no problems, other than cost, using nothing but Seachem fertilizers.


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