Modular Marine 1600gph overflow install question

Hi,

Just received this overflow for my (planned) 75 gallon tank and have a question on drilling the tank for the installation. The tank is a standard trimmed tank. The instructions say to mount the external box as high as possible to keep the water line above the trim. The package included a template but the instructions also warned about making sure there is enough clearance to be able to install and I guess remove the internal skimmer box and its removable cover so as to not interfere with the interior tank trim.

After measuring about a dozen times I came up with providing a 1/8" clearance between the top of the template and the inside bottom of the trim inside the tank. This looks like it would still enable me to keep the water line above the trim.

Has anybody had any experience with installing this kind of overflow on a standard trimmed tank? Am I on the right path?

Also, the instructions seem to say to position the external box to mark the holes for drilling. Seems like it makes more sense to position the template on the inside of the tank and mark the holes for drilling. Is there anything wrong with drilling the glass from the inside of the tank or does it have to be from the outside? If so, not sure how I can accurately mark the holes and drill from the outside using their instructions since it seems tough to get a marker inside the external box to mark the hole locations like it says in their instructions. Seems easier to use the template inside the tank.

Any help or advise is appreciated. Their website wasn't much help.

John
 
Did you email Modular Marine to see what they said? I'm looking at one of their overflows for a peninsula tank.
 
It is better to drill from the outside, that way any chipping will occur on the inside and not interfere with the seal between the external box and tank. If you drill from the inside just go really slowly at the end of the hole.
 
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