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Filamentous Algae - An Experiment With Excel !!


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#1 Brett

Brett
  • Forum Member
  • Joined: 15-September 04
  • Location: Perth

Posted 14 December 2005 - 10:44 PM

Many of you will be aware of my long running battle with various forms of filamentous algae. My tank has been infested with at least three forms of filamentous algae for over twelve months. I have attempted multiple interventions, from changing photoperiod and lighting to numerous nutrient manipulations. All to no avail.




Finally I arrived at the point were I was going to start again, but decided to give a last, desperate chemical attack. I had read on the forums that some people had success with using Flourish Excel at twice the recommended dosage. I hasten to add that Excel’s manufacturers make no claim for algae control and you dose above the manufacturers recommendations at your own risk, as you will see.

As it is extraordinarily difficult to identify algae, we are left with descriptive names that can be misleading. I had at least three forms of algae that I will refer to as “fur”, “staghorn” and “thread”. Fur algae has many short strands that are very close together, like the fur or pelt of an animal. Staghorn algae form from a single point, which is often quite firmly fixed, and have multiple branches, like a weeping tree. These form clumps of algae between leaves. Thread algae forms long threads, up to 30cm in length. When the tank was at its worst all these types were mixed in together.

Prior to treating the tank I removed as much algae that would easily come away and did a couple of large water changes. Plants were thinned as many were badly damaged. Extra current in the form of a power head was added.

Excel (polycycloglutaracetal) was added at twice the recommended rate. This totalled 55mls in my 220 l tank. I added it all at once, straight to the tank allowing the circulation from the power head and canister filters to spread it about.

After a week the effects were becoming obvious, nearly all of the “fur” algae had become white in colour and appeared dead, it was also starting to break away from the leaves of plants. There had been practically no regrowth of any types of algae, but the “staghorn “ algae had been less obviously affected. Equally as dramatic was the effect on the plants. All of the Vallis leaves had died and the Bolbitis fronds had developed black segments on them. Thes blackened areas eventually rotted away. Some of the Bacopa stems seemed to be rotting.




By the second week the impact had become more clear-cut. This was when I started to vacuum the dead algae up, which also resulted in some further water changes. By this time the Vallis had started to shoot again, although many of the older plants were completely killed. Bacopa was growing back quite strongly. Most of the “Fur” algae had been killed and was now coming away from the leaves. A lot of these leaves were badly damaged, but some, particularly on the Anubias seemed almost normal. This was surprising given the length of time they had been completely covered. The Excel seemed to have no affect on the Crypts, Swords, L. repens or R. rotundifolia or Ambulia. There is still viable clumps of “staghorn” algae, particularly deep within the A. nana plants. This area probably had reduced exposure, as the water flow within these “thickets” is probably poor. Most of the “staghorn” algae that was attached to the gravel seems to be gone. This may relate to more aggressive gravel vacuuming, but I suspect the algae was weakened first.


The pictures above show my Java fern "Windelov" before (left) and after (right) treatment.

Clearly this experiment demonstrates the algicidal effects of double strength Fourish Excel. The treatment is not without its problems, proving toxic to Vallis, and to a lesser extent Bolbitis and Bacopa. Its effect on different forms of algae is also variable, being particularly effective on the fur algae, which was almost completely destroyed, but less pronounced - though still effective- against the staghorn algae.

I would appreciate feedback and comments from other forum members, both on there interpretation of these results and experience with other algicides. To reduce bandwidth usage I will close this thread and open a second thread without any pictures in which to post comments.

Cheers
Brett




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