Bought a used tank

[Ascartes]

Hello everyone, I just bought a used 90g tank that was used for saltwater over a year ago and has just sat since then.

I was thinking about basically redoing as much of it as possible (it has drain line for sump and I don't like where the return line is)

Since the bottom already has a hole drilled in it, is it safe to assume I can drill more?

Can I just put a bulkhead or glue a cap in to cover an existing hole in the bottom and then just cover with sand/rock to 'remove' it?

I also am not really a fan of the peninsula overflow thing someone put in it and thinking of making it 2 corner towers instead of the entire end being the way it is, unless someone has an idea of why it is better. I've never had a reef larger than a 40B and it has an AIO so completely new to sumps as well any advice is appreciated, I'm probably going to end up redoing that as well.

Thanks in advance!

 

[Peace River]

It is a reasonable assumption that if it has one hole then you can drill another, however I would still use the polarized sunglasses test to make sure. Good luck with your project!

 

[vetteguy53081]

With existing hole it is tempered and can accommodate additional hole
Try to leak test tank before further investing in it
Corner towers are my preference for flow distribution

 

[Gtinnel]

I would suspect that the glass is not tempered if it already has a hole, but I know glass can have a hole drilled in it and then tempered afterwards. I don't know about aquarium manufacturers but with glass in general a hole doesn't guarantee you can drill another hole.

Absolutely test to make sure the glass isn't tempered before drilling.

 

[dhnguyen]

I'm not a fan of drilling the bottom myself. What about capping the existing holes and drilling the back pane instead? Then you could just use a couple slim internal overflow boxes like the eshopps eclipse

Eclipse S Overflow Box (600 GPH)

Quiet, Slim, Plug & Play The Eclipse aquarium overflow system consists of a slim black box that is mounted inside of your tank and a clear external box that mounts outside of your tank, to transport water down to your sump with as little noise generated as possible. The DIY project only takes a...

www.bulkreefsupply.com

That will allow for more tank real estate than having 2 corner towers.

 

[Ascartes]

Thanks for the suggestions so far, I need it to be through the bottom unfortunately just due to the nature of the stand (all of the side walls are magnetic panels and it looks very clean having them on properly).

What exactly is the test to know if it is temp or not?

 

[ying yang]

Here video to use POLARISED glasses to check.

Also tanks i have had that are tempered have had stickers on saying its tempered glass

 

[vetteguy53081]

I leave drilling to a glass shop or someone who has done it before (typically from a local aquarium club)

 

[zalick]

I had holes in the bottom of a glass tank that I covered with the same thickness glass and silicone. Just had some glass squares cut about an inch wider than the holes all way around. Silicone them down. I think that’s safer than a bulkhead sealed off.

 

[ying yang]

I had holes in the bottom of a glass tank that I covered with the same thickness glass and silicone. Just had some glass squares cut about an inch wider than the holes all way around. Silicone them down. I think that’s safer than a bulkhead sealed off.

Yeah i was going to add silicone some glass in over the holes not used instead of capping off.
Once watched joey on " diy fishkeeper" doing a video repairing bottom glass cracked but same kind thing