[eldalote2]

my 20 gal has limited space and i was just wondering if leaning the rock work against the glass would be safe.

[e_baer]

It would be safe, but the glass would be incredibly difficult to clean. Also, it will also hinder the flow. But, as long as you strategically place powerheads it should be fine!

-Elliott

[glampka]

Personally I don't like putting the rock on the glass. Should a fish die back there you'll have to tear the aquascape apart to get it out. I've also found that fish will like to hide back there so that wonderful looking fish you just spent $$$ may not be seen too often. Flow is another big concern. Lack of flow will cause detritus to collect behind the rock more.

[JackedupSOB]

I did it in my tank just because my tank is not very wide in relation to its length and so far everything seems fine.
However, some fish do like to hide back there alot particularly my kole tang

[pogodzib]

My tank has a ton of rock up against the back glass. Like people have already said, the key is getting flow into those areas and dealing with dead fish. In large tanks, you don't need to worry about pulling out a fish if it dies, but in a 20 gal tank, you'll want to make sure that you can get to all areas of your tank. Shy fish will hide in rock work, no matter how it is configured, so I don't worry about where the fish can hide. In fact, it probably makes them less stressed because they do have places to hide.

[lynnvangsnes]

I have several pieces leaning against the back of the tank. I have a small "spray bar" that keeps the water circulation behind the rock. They are correct in that if something does die, you will have to uproot everything to find it.

[ozzy_200769]

I had a 55g ( upgraded to a 75)
w/ 120+ of lr and alot of coral.
I too had to aquascape my tank w/ the rock going against the glass, I never had any problems w/ my tank
because of that.
My 75g doesn't have any against it and I still have a problen cleaning the
back glass, as far as fish dieing I can't find em any way, my hermits etc. take care of the corpses.
(Knock on wood I have only lost a couple fish).

[pogodzib]

A fish dying in a 55 or 75 gal tank usually isn't a problem if you have hermits, as long as the fish isn't really large. The water column is large enough to sponge the increased nutrient spike caused by the dead fish. In a 20 gal tank, it can be fatal to both the remaining corals and fish.