I have just read the whole thread and a few things strikes me.
First it must be very hard to decide what to do with so many writing in the thread.
And maybe I will not make i easier now.
First I think the tank has a bad design of the filtering system. The skimmer shall be the first in the line after the surface owerflow.
It ventilates out a good part of the ammonia and so it will be a slower buildup of nitrate. I would take out all mechanical filters because they are populated with nitrifying bacteria. In my shop I have almost 40 tanks but no mechanical filter.
Second thing to do is the ICP test. A major rule in the reefing hobby is: Never do anything without knowing.
You mentioned crabs. They and the blenny could maybe are the reason that there is no algae on the rocks and the bottom. But in that case it should come some on the front glass. What kind of crabs do you have?
Coralline algae need good water values to grow. They dont grow well when the nitrate is high. Also the calcium, magnesium and kH values are important.
First it must be very hard to decide what to do with so many writing in the thread.
And maybe I will not make i easier now.
First I think the tank has a bad design of the filtering system. The skimmer shall be the first in the line after the surface owerflow.
It ventilates out a good part of the ammonia and so it will be a slower buildup of nitrate. I would take out all mechanical filters because they are populated with nitrifying bacteria. In my shop I have almost 40 tanks but no mechanical filter.
Second thing to do is the ICP test. A major rule in the reefing hobby is: Never do anything without knowing.
You mentioned crabs. They and the blenny could maybe are the reason that there is no algae on the rocks and the bottom. But in that case it should come some on the front glass. What kind of crabs do you have?
Coralline algae need good water values to grow. They dont grow well when the nitrate is high. Also the calcium, magnesium and kH values are important.