Hardscape and stagnant water
I am making a somewhat large hardscape element using Rocks and Apoxie Sculpt epoxy putty. It will be about 15*15*20cm in a 12G tank.
The element will be placed in one corner and will have a substrate & plants on top of it in a bowl. So 3 sides of it will be against the aquarium walls and floor. I want it to be right in the corner and not for example 1cm away from it so that fish might get behind it.
With epoxy putty I am able to make it match the aquarium corner shape quite precisely (max 0.5-1mm gap), but I am still worried about the stagnant water that might/will get behind the element. I am unable to locate filter input/output or any other vessels to pump air/water to that gap.
The aquarium hardscape will be in use hopefully for many years and I am unable to tinker with it without tearing the whole thing apart. Therefore I want to get it right the first time.
A. Try making it as precise as possible and then seal the element from all 3 sides using silicone.
B. Try making it as precise and possible and leave it unsealed so there will be some very very minor water circulation.
Or are both of them a bad idea?
As far as I see, if I choose A, it is possible that water might still find a way between the element from some tiny hole, but the exchange with open water and sandwiched water is so minimal that there should be no issues? I think this compares to a small amount of substrate that is never stirred?
With option A, there is no risk of having sand or newborns stuck to that gap and no gap to clean.
Am I good to go with option A?