@klp It´s not an under gravel filter as 40 years ago - not even a reversed flow under gravel filter as EHEIM introduced in the eighties. It is intended to be a DSB but with a very tiny flow upwards. I´ll try to create a denitrification area in the bottom of the DSB and need a tiny flow just to have the water going through the bed and also for bringing down a fast organic carbon source to the denitrification point. Which source it will be – I haven’t decided yet. There is one source that no one use yet which I'm mighty tempted to test – skim mate from the skimmer. Pure bacteria that will create an anaerobic zone that in the long run can act as an internal fast organic carbon source. The environment I´ll create will also be rich in carbon dioxide and the pH up through the bed will hopefully act as an internal calcium reactor. The bottom water will be rich in both phosphate and ammonia and maybe I´ll use this resources also. Over the DSB I will have a reversed refugee of macro algae. If I succeed to have a tiny flow through the DSB upwards – I maybe only run the flow during night so I´ll bring up both carbon dioxide, phosphate and ammonia to the macro algae.
This build is a test aquarium where I have combined a lot of ideas. I´ll follow up it with measurements and also experiments to see if I will be able to regulate what’s happen. There is Dutch ideas that are rather similar with mine but how similar I do not know because I have not study their work at all.
I´m aware of that I´ll maybe will construct one of the best hydrogen sulphide reactors in the world – therefore I will handle my return pump in such a way that it will not start in 15 minutes after a power break – it will not start before the skimmer working good. I will also have at least one oxydator in the sump, maybe a small one over the DSB also (oxygen neutralize hydrogen sulphide momently)
If all of this work the way I want – I will have a stable biological driven system – and that´s the goal
Back to the build – It will not be any pictures today because I realize that I have to test the whole system for leakage – before I mount background and build the DSB :)
Sincerely Lasse