Having a lid cut, what's the best option ?

[Andy D]

I would be concerned with it dripping down the side if it covered the rim completely and wouldn't it be a problem with gas exchange?

 

[James O]

Drill a hole or two. With adequate surface movement you should be good to go

Having said that, a small gap around the edge (internal lid on clips) will be more than enough

 

[stu_]

There'll be a gap at the side where the Lily pipe sits.
It's low tech atm.
Will use clips and thick acrylic.
Thanks for all the info everyone

 

[Trevor Pleco]

I gave an opinion on a previous post

 

[stu_]

I gave an opinion on a previous post

So you did Trevor,and I thank you for it.
I lost sight of it,amongst all the talk of 3,4,5 mm, will or won't bow.

 

[Trevor Pleco]

to confuse you further I have an old 5mm perspex lid which is bending quit a bit. I also have glass with your clips on another small 25cm planted tank and that's a bit of a fiddle and pain to get off each time I want to do do something in the tank, whatever the case keep a reasonable gap at the back for reducing condensation, piping and to feed.