Hi and welcome to the forum

I guess this person means possible problems with the connectors. Normally AC is using plug n cool connetors for tubes with an ID of 6mm and an OD of 8mm.

AC also offers screwed connectors with 8/10mm.

I don't know what 7/16" ID 5/8" OD is in milimeter but I'm pretty sure it will not fit the standard connectors. Maybe you will have to use an adapter or special connectors.

I have seen so many aquatubes in typical american big-bore setups. It should be no real problem to use it - you only need the right connection stuff (which I don't know).

7/16" = 11.113mm

5/8" = 15.875mm

I guess you won't be using pushfits on that

I'd say your choices are;

1. Rebore a pair of the Aquatube ports (probably one in the base and one in the side) to suit a larger fitting - 1/4" rather than 1/8" if possible. You'll be compromising the anodised finish of the Aquatube by doing this, so will have to think of other ways to protect against galvanic corrosion - carefully applying sealant around the fitting on the inside perhaps?

2. Use manifolds/splitters to split your loop into three and use all three ports in the side for in, and all three on the base for out. This can look a bit messy, but is the most practical solution that keeps the res in your loop.

3. Use the Aquatube as an air-trap only, without putting your loop through it. You'll need to put a T-piece in your loop - preferably before the pump, and just run a single line up to the Aquatube.

Whatever you decide, good luck