A few days ago I decided to do a 75% water change in the 5 gallon riparium so that I could replant the java fern, which was less than happy with the light in the corner it had been in. While doing this, I had to disturb the substrate (a mix of mineralized soil, clay, and flourite). I refilled the tank with treated tap water and added my guppies back in. All was well for a few hours until I noticed the water become cloudy and one of the guppies gasping at the surface. Alarmed, I immediately did a 25% water change and the guppy recovered quickly. The next day the cloudiness was back and the same guppy was again stressed while the other was fine. Again, a 25% water changed fixed the situation. This continued until today when I did another 75% water change to try and get things back to a healthy equilibrium. I’ve been mystified, honestly, as to the problem.
But, a mere 1/2 hour ago, I decided to do a full water quality check and realized that the water was incredibly soft, which was strange considering my tap water is usually rather hard. Then it hit me – I disturbed the substrate and released clay into the water! That brought the water hardness down considerably and stressed the hell out of the less hardy of the guppies (not to mention I’m pretty sure he didn’t appreciate filtering clay through his gills…). Every time I did a water change I fixed the clay issue temporarily until more released. So the plan is to do a full water change tomorrow and add a 1/4 inch of flourite and gravel as a top coat to keep the clay/soil mix contained. If any cloudiness remains, I’ll set up a temporary tank for my finned friends while I continue to remove the dissolved clay from the water.