Chapter 21. Does using aged water reduce cyanobacteria in my aquarium?

If using aged water (AW) did reduce the amount of cyanobacteria in my aquarium, if it is really was the factor responsible for the reduction I observed in Chapter XI, then I would expect it to do so reproducibly and over a similar amount of time. In Chapter XI I noted that I observed a dramatic reduction within five weeks, so for me to be convinced this time I would have to see a dramatic reduction over a similar timescale.

Week 148. Cyanobacteria (possibly green Lyngbya mats and brown unicellular cyanobacteria mats) from a freshwater aquarium. Photo taken Immediately before the first AW change.

As you can see, by week 148 species 2 was growing well on the Moss Ball and Amazon Sword but also on the tank walls, bog wood and gravel (the gravel was more affected at the far end of the tank). As I mentioned in Chapter 19, I was pretty efficient at removing it from the plants at this point and ruthlessly efficient at removing it from the tank walls and gravel, so most of what you see here will have grown in the week since the last water change.

Week 154. Immediately before the seventh AW change.

I could argue that there was less cyanobacteria in the tank at this point but I can't claim that the reduction had been dramatic. The bogwood was still almost covered and the Moss Ball. There was still cyanobacteria on the gravel and tank walls.

Week 154.

I think the best I can say is that the cyanobacteria problem hadn't got any worse, which is something because in my experience cyanobacteria problems always get worse. But there was little evidence that using AW is worthwhile. It occurred to me that one reason why it had failed might be the condition of the container I age my tap water in.

Week 149.

The inside had become almost entirely coated in a slimy layer of what I assume to be bacteria. So in an attempt to replicate the conditions when I first used AW and the container was new, I gave it a really good clean with a bottle brush and continued the weekly AW changes.

Week 160.

I think it's fair to say that over the next six weeks there has been a dramatic reduction in the amount of species 2. There is still some on the bogwood and gravel, but the plants are mainly clear, and there is none on the tank walls. Interestingly, the colonial unicellular cyanobacteria has returned on the Amazon Sword leaves. It's like the cyanobacteria succession I saw in Chapter 19 is happening in reverse. If that is true then over the next few weeks I should see a reduction in the brown unicellular mats. At that point I will switch back to fresh tap water in the expectation of seeing the succession played out once more.

Chapter 20. Cyanobacteria identification 6 (species 2 and 3)

This is mainly as an excuse to post more microscopic images of cyanobacteria, but I thought I would explain why I have started calling species 2 "possibly Lyngbya" and attempt to identify species 3.

Three filamentous cyanobacteria from a freshwater aquarium. Identified by an amateur at the genus level as;  Lyngbya (thick filaments), Jaaginema (sinuous filaments), and Romaria (short filaments).

From Chapter XIV (where I wrongly identified species 1), I know that species 1 is 2 micrometers wide because I measured some filaments under the microscope using eyepiece and stage graticules. By my calculations, depending on which photo I take measurements from, species 2 is somewhere between 8-10 micrometers. So, using the same key I used to more accurately identify species 1 in Chapter XVI, we get.

Q1. Are the filaments 3 micrometers wide or more?  A-Yes. Q2. Are the filaments cylindrical, long, sometimes constricted at the cross walls, but cells not barrel shaped or sub-spherical? A-Yes. Q3. Are the cells short, always shorter than one half the cell width? A-Yes. Then we come to the crunch. Q4. Are the filaments in vegetative state always without sheaths (if present formed only under stress)? Sheaths again! The problem is that the species 2 sample I examined in Chapter XVI  which showed clear evidence of sheaths, could have been stressed because it had sat around for a week. So I examined a fresh sample.

Filamentous and unicellular cyanobacteria from a freshwater aquarium.

No evidence of sheaths in this sample, but note the dark stripes along the filaments, it is at these necridia that the filaments fragment. I added some very small glass beads to the sample and vortexed briefly. The idea was that if I damaged the filaments I might see evidence of sheaths.

Fragmented sample of filamentous cyanobacteria from a freshwater aquarium.

It seems to me that the filaments have fragmented at the necridia. Many filaments now seem to have the remains of necridia at their end. This could happen if the filaments lacked sheaths so it doesn't tell me much.

Diatoms alongside unicellular and fragmented filamentous cyanobactera from a freshwater aquarium.

These fragments don't even have the remains of necridia at there ends. Maybe the fragmentation was too vigorous. What I really need is to slightly damage the filaments. Perhaps in the future I will find a way of doing that. But there is some evidence of sheaths here.

Fresh cyanobacteria sample from a freshwater aquarium showing evidence of sheaths.  Possibly Lyngbya.

So, if it's Q4. A-No to trichomes always without sheaths then it's Yes to "Trichomes in vegetative state always within distinct sheaths (only hormogonia and reproductive trichome segments can be without sheaths)". Q5. Do the filaments contain one trichome per sheath, forming mats? A-Yes = Lyngbya.  Of course it's possible that I have a mixture of species, some with sheaths (Lyngbya) and some without (Oscillatoria).

Possible Lyngbya filaments showing evidence of sheaths.

If you search for pictures of Lyngbya you will find some very similar images to the species 2 photos I have posted in this and other chapters.

Finally species 3. Q1. Are the trichomes less that 3 microns wide? A-Yes. Q2. Are the trichomes without sheaths or within simple, thin sheaths (when present always one trich/sheath) solitary or in mats, trichomes isopolar (both poles with same morphology)? A-Yes. Q3. Are the trichomes without sheaths, but may possess wide or diffuse mucilaginous envelopes? A-Yes. Q4. Are the trichomes straight, wavy, or irregularly coiled? A-Yes. Q5. Are trichomes mainly short, curved or irregularly coiled, usually only few celled, disintegrating , sometimes enveloped by an indistinct wide mucilaginous envelope, neighbouring cells occasionally disorganised? A-Yes (I guess) = Romaria. I can't find any photos of Romaria so I think I'm on shaky ground with this one. Correct me if I'm wrong.

Chapter 19. The rise of the Cyanobacteria.

Week 137

Week 139

So to re-cap. By week 137, 13 weeks after reverting to standard tap water changes, a uni-cellular cyanobacteria had largely covered the Amazon Sword plants and was growing in the Java Moss. There were also small patches of species 2, particularly in the Java and on the Moss ball. It is strange that the Elodea and Hygrophila  seem much less affected. But the cyanobacteria outbreak (if you can call it that) was mainly a plant problem. The gravel and tank walls were largely clear. Then in week 139 the brown colonial mats on the Amazon Sword plants started dying.

Week 141

Week 143

By week 141 they had died right back, this effect was tank wide. I don't know what caused this sudden population crash, or the gradual increase before it. But I may as well state that for the 15 previous weeks the levels of nitrate I measured varied between 0.2 and 1.0 ppm with no general trend I can see. No explanation then for the re-appearance of what I assume are unicellular cyanobacteria on the Amazon Sword, bog-wood and, importantly I think, the gravel (week 143 above). It's also growing on the glass. It is at this point that a cyanobacteria population becomes a problem, because anything that obscures the view or makes the gravel look dirty is an embarrassment.

Week 145

Week 146. 

In week 145 I forgot to photograph the tank before I had cleaned the tank walls. This is why they look clear, but you can see that there are species 2/brown mats on the gravel and the Hygrophila, in fact all the plants are now affected.  Notice how red the brown mats can be, it reminds me of the cyanobacteria seen in reeftanks. By week 146, species 2 was starting to dominate the tank. Nitrate levels had dropped to undetectable for weeks 144-146, but I see no reason to think this has caused the recent increase in cyanobacteria. It could just as easily be a consequence.

If you compare these pictures with the one at the beginning of the previous post, it's clear that cyanobacteria (of one sort or another) have increased dramatically over the last 20 weeks. It's the classic pattern, the more I syphon off, the more grows back. The traditional advice would be to increase the frequency of water changes, or maybe to add nitrate, but I know from experience that would be futile (see Chapter VII).

I would like to make two points about my new cyanobacteria infestation in comparison to the previous species 1 (Jaaginema?) in terms of aquarium maintenance. Firstly; the new species do not smell as strongly. The characteristic smell of cyanobacteria is apparently due to chemicals they produce, mainly geosmin and MIBs. They are said to give cyanobacteria an "earthy smell" but I prefer to think that soil smells of cyanobacteria. In all my reading about cyanobacteria identification and classification I have not seen smell mentioned as a criterea to define genera. Maybe it could be. What I can say is that species 1 (Jaaginema?) produces lots of geosmin/MIBs whereas species 2 (Lyngbya?) and 4 (Unicellular) do not.

Secondly; they are much less sticky (see video). During the first infection, it was very difficult to syphon a species 1 mat off a small plant and impossible to syphon it off the gravel. It would always hang on to enough gravel to weigh it down in the syphon tube. These new species come away nicely. So, the tank doesn't smell and it's easier to remove the new cyanobacteria, but it still gives the tank that primordial vibe. I prefer the verdant green spotless tank of week 126 so I will try and reduce the cyanobacteria in the same way as described in Chapter XI.

Chapter 18. Cyanobacteria identification 5. A New Player Emerges.

"Mr Bond, you return with the tedious inevitability of an unloved season"
                                                                                               Hugo Drax

It's week 146 and it's time for an update of my increasingly inaccurately named blog. I have spent the last 20 weeks waiting for a return of my cyanobacteria problem, and my patience has been rewarded. The difference is that this time I was expecting it. As a result I don't have to trawl through my photos to find rare shots of the tank, or take stills from videos, in order to show the epidemic develop. I have photographed the tank before every weekly tap water change, and measured nitrate and pH. So I have a pretty accurate record of the incidence of cyanobacteria in my tank, as well as at least one variable (nitrate) often quoted on tropical fish forums as being important in determining the incidence of cyanobacteria in fish tanks. So, hold on to your hats.

Week 126. The best of times.

Looking back, this was the best the tank had looked since week 80. The plants and gravel are cyano free, but notice the brown patch on that Amazon Sword plant? It looks like a patch of dead cyanobacteria and I expected it to peel away and be easily syphoned off.

Week 129. 

But it didn't peel away, in fact it seemed to slowly spread so that by week 135 some of the leaves were completely covered. This new brown organism also grew in the Java Moss.

Week 135.

Week 135 also was the time I started to observe an increase in cyanobacteria numbers. There had always been sporadic localised outbreaks, but they were easily ignored. In the photo below the brown organism is growing alongside what looks a lot like species 2 (see Chapter XIV) in the Java Moss.

Week 135. 

I suspected that the brown organism was species 3 from Chapter XIV because species 3 had such dark pigment. Some microscopy was in order so I took a sample from the Java Moss that had some of the brown material and some of the blue/green.

Unicellular organism alongside a filamentous cyanobacteria species (possibly Lyngbya) from a freshwater aquarium.

The filaments are familiar and look exactly like species 2 but I was not expecting to see the single celled organisms. So, what are they?

Higher magnification suggests that unicellular cyanobacteria are present (possibly Chroococcus and Pleurocapsa species).

They are cells that obviously reproduce by binary fission but that do not form chains. There looks to be multiple forms in this sample, note the groups of four cells (arrowed). They appear to contain a pigment and that pigment is distributed evenly throughout the cell. Their pigment is a different colour to the yellowy pigment of diatoms. I think they're cyanobacteria. And if I search phycokey I can find some similar looking unicellular colonial cyanobacteria. So it seems that a new species of cyanobacteria appeared in my aquarium. It is capable of forming mats and has a definite preference for growing (very slowly) on plants.

Week 126

Week 129

Week 133

Week 136

I say "new" species of cyanobacteria but I suspect it has always been in the tank. I had probably never noticed it before because I, like most fish keepers I think, always assume that a brown coating on plant leaves is diatoms (brown algae). But I think I can say I have never noticed it in the quantities seen by week 136. So it seems that the die-off of species 1 (see Chapter XI), and general reduction in cyanobacteria I observed between weeks 112 and 120 stopped at some point.  Conditions for cyanobacteria seem to have improved and this resulted in the visible appearance of a new cyanobacteria by week 126. But, apart from the brown leaves, the tank looks great so it wasn't a problem in fish keeping terms.  I didn't feel at this stage that there was enough cyanobacteria in the tank to test if using aged water (AW) does have an effect on cyano, but I did think the tank was heading in the right direction for such a test to be done.