I’m planning to do a large water change tonight, in preparation for the fish, and I would also like some clear readings for the record, so I know how much the wood will affect the water after it is added. This morning, the readings were:
- KH: 9.5 ° (170 ppm)
- GH: 21 (376 ppm)
- ammonia: 0 ppm
- nitrite: 0 ppm
- nitrate: 80 – 160 ppm
- pH: 8.2
I expect KH, GH and nitrate to drop after the water change because my tap water readings are lower.
Unfortunately, the diatoms are still there and getting worse, so hopefully, the water change will help improve the situation. I also have a Malawi aquarium, which, for those of you who do not know, is a Lake Malawi simulation, with a lot of rockwork and no plants because the fish which live in the lake naturally graze on algae and have a habit of mistaking plants for algae, which means that most plants would not survive for long. In this rocky and plant-free environment, I also often see diatoms, and as is currently the case with this aquarium, the Malawi setup also has high nitrates, so I assume, given that the general hardness is the only other common factor between the two aquariums, that the nitrate is responsible. I have also noted the appearance of cyanobacteria, an algae-like bacteria, today. I hope this is also related to the high nitrate levels.
I performed a clean of the aquarium, including glass and filter, and changed 36 litres of water, which was approximately 80%. The water readings after the maintenance were:
- KH: 10.5 ° (188 ppm)
- GH: 18 (322 ppm)
- ammonia: 0.25 ppm
- nitrite: 0 ppm
- nitrate: 10 – 30 ppm
- pH: 7.8
The results indicate that my tap water has changed since I took the original readings: my tap water pH has dropped, while the KH has risen.
I also added the wood, right after the water changes. It has now picked up the rich red which gives it the name of “red moor wood”, but is being slow to water log.