After I put the new plants into the aquarium on Saturday, the water went very cloudy, and no matter how much coagulant I added, it just got cloudier, so that by last night it was so opaque I could not see any of the denizens of the tank, except I did catch a glimpse of one of the shrimps I caught at Marribank the weekend before last. It was motoring along right up against the glass. I was pleased to see that at least one had survived. However there is no fun in staring into a tank of milky water.
I cleaned the filters again last night, as I had every night since introducing the new plants. I was getting nowhere. The last time it clouded up like this I had to capture all the little creatures, empty the tank, wash the gravel, refill the tank with tap water, dechlorinate and age it, get the temperature right, then reintroduce the livestock. That is a day’s work at least. There has to be a better way.
The milky exudate that came from the dacron and sponge filters was obviously a fine colloid and the aquarium coagulant I was using was clearly not up to the task of making the particles large enough to be captured in the filters. I can only speculate why. However I recalled that when I was reviewing the water treatment plant in Wainuiomata as part of my drinking water assessor training, I had learned that sometimes organic material from the bush is slightly acidic, and therefore difficult to flocculate. I had already tried to counter this possibility by adding a little baking soda as a pH buffer, to no avail.
At Wainuiomata they countered the problem by actually introducing dirt. They also used air flotation so that a curtain of tiny air bubbles lifted the floc to the surface rather than trying to settle it to the bottom in the usual manner. I could not do that, but maybe I could increase the floc size somehow.
After a bit of thought, I opened up the cyclone of my bagless vacuum cleaner, and took out a small handful of house dust. It was comprised of sand, dust and fibres. The usual dust bunnies and carpet sweepings. Hoping there was nothing in there toxic to fish and yabbies, I threw it into the aquarium, gave it a stir, and went to bed. This morning I saw the water was almost back to clear, and by lunchtime it was as sparkling and polished as it had been last week. A remarkable change in 14 hours. Tonight I will change the labouring filters once more and hopefully we can return to the weekly routine.
I really am a clever bastard.