Yeah, a 25mm bulkhead is just bigger than 1/2" which can only do 300GPH/1200LPH worth of flowrate. I'd suggest a 45mm hole for a 1" bulkhead, that's how I did mine

So I am going to sell them, then use the tank as an extra for sump as I have said or get some dwarf puffers, maybe something else though.

In the end I used what I had on hand, white spirit.It seemed to work ok, it made the sylocone week and when I took a bit off from the inbetween the overflow and base glass I just slowly pulled it and it came.When I was cleaning the area to drill I caught myself on a hooked shape peice of glass and it slit through my finger
Oh well...I'll be finalizing the plan tonight so hopefully my dad can pop back in there soon.The time this has ran on with me doing absolutely nothing, except cracking the tanks first base, is pathetic lol.
It says payment completed on paypal, and its the right credit card...