My sand is a problem. I do water changes every week and I have tried all of the ideas that others have posted in my separate post specifically about this problem, but there is no change. I put on a pre-filter sponge which should at least help this filter not get damaged by the sand, but it is not doing anything about the fine particles of sand that are floating around constantly in the water. I am getting really paranoid that the ultra-fine particles are harming the fish. I actually think a substrate change is in order. The sand is the same throughout. You can see in one of the photos (assisted by my lovely goby) that the sand has the same texture even under the surface. I've been giving this a lot of thought and I do not think that the ultra-fine particles will ever come out in an aquarium. I have the same sand in my kids' sandbox outside and even after several years out in the elements, the sand still covers the kids in dust when they play in it. Although others have had good luck with their play-sand, the brand at my store was not good for aquariums. I am going to get aquarium sand and hope that all of the plants don't die in the process of being transplanted.
Here is why I am so freaked out. Two flame tetras and two pearl gouramis have died over the last few months and the other gouramis and several other tetras are looking poorly. I have been testing every other day and the water parameters and water quality are always excellent. Ammonia, Nitrites always 0. Nitrates never even getting to the 5ppm color on the test. The fish that are natural sand dwellers (the cory catfish and the gobies) are totally fine. They are behaving as they always have. The other fish (tetras and gouramis) all look tired. Slow swimming, not coming to the surface at feeding time, hiding, resting on the bottom. I suspect that constantly "breathing" fine sand particles may be harming them. A substrate change may help. I can't stop the sand from getting kicked up. You can kind of see in one of the pictures the cories kicking up some sand. The picture doesn't do it justice though. They are constantly kicking up sand. Some of it sinks back down, but much of it floats around.
I bought aquarium sand for my son's 6.6 gallon triops aquarium and it washed clean in 2 seconds. There was no floating cloud of fine sand particles and mica. What sand got kicked up by the water hose, quickly settled back to the bottom. While the particles are larger than my existing sand, they are still smooth, so should be fine for the cories to sift. Since they are heavier, they shouldn't float around in the water.
If anyone has other ideas about what could be killing my fish, I am open to hearing it. They show no sign of disease other than the symptoms I have already listed (slow swimming, decreased interest in food, hiding, resting on the bottom) - no flashing, no spots, no cottony growths, no worms, no streaks. Actually, wait, a few of the tetras look paler than they used to. The red color is rather faded looking. I know that can be a sign of tetra disease, but the gouramis' coloration looks fine. One of the gouramis did show signs of having been attacked by the others (missing scales, torn bottom fin), but that is injury not disease. Perhaps the aggression is exacerbated by the stress. But the question is, stress from breathing sand or stress from disease? AND if there is disease, are the fish open to it because they are constantly stressed from breathing in all that sand?
Sorry for the long post. I am just really worried about my fish.
