John S
Member
One of my tanks has been running for about 4 years now with a mixture of eco complete and inert gravel. I use CO2 and EI and syphon the top of the gravel weekly. At the weekend I decided to move large piece of wood and was going to add some plants but the substrate under the wood has gone rock hard and clumped together. You struggle to break it up with your hands. Other areas of the tank seem fine.
Does anybody know what causes it?
Does anybody know what causes it?