i used the ADA brushes and the Eheim brush set too. to clean inside of these glasses are painful especially if the diameter is small and you have more curve. ADA came out with a new brush for 13 and 17 glasses called Spring Washer. This is a simple but pretty cool tool to clean easily all kinds of glass inlet and outlet.
You can ping TGM to see if they have it on stock or they can preorder it to you i bet.