Concrete Recommendations

[Salt Addiction]

So wife is thinking about an eel for one of our established tanks and I am wanting to buff up the support on the rocks just in case. Since this is all very established rock I don't want to dry it given it would kill everything on it. Anyone know of a good concrete that works for LR underwater? I tried Coralcrete and it was pretty much garbage.

 

[Greybeard]

I'd probably using an epoxy of some sort... I've used IO Holdfast epoxy sticks with good results in the past.