Just planted my tank up and have just read that the subsatrate deapth should be only 2 to 3 inch deep where as mine is between 4 and 5 in the front and at the back 4 to 7 is this a problem i leveled out about a ich of deponit mix professional in bottom.

Chears Duncan.

What is deponit mix professional? Is this an aquatic substraight?

I had the same questions with my high light planted tank, though I only had 4 inches in the front and about 5 in the back.

I really don't know if this will be a problem. Anarobic bacteria can grow in deep substraight and create gas pockets, but I don't know if this is bad for your tank.

Try www.plantgeek.com for a forum with more sophisticated planted aquarium people.

Thats a bit excessive particularly if its a particulate (pun intended - such as sand). As PK said if its not regularly stirred detritus will build up inside and form toxic gas pockets which when released can be fatal to fish. If the majority of the depth is just a gravel-type substrate I wouldn't worry, but it is still excessive. =P