Cardboard - is it safe?

[SpidermanTUba]

I have an aquarium with an undergravel filter and gravel.

I'm replacing the undergavel filter with an external canister filter, and would like to replace the gravel with a fertile substrate of clay/sand/peat moss/soil in order to grow plants.

Rather than cause a massive shift in water chemistry by draining the water, replacing the substrate, and putting the water back, which the fish wouldn't like, I think it would be better to make the conversion gradually.

I'm thinking I could use cardboard planters, gradually replacing the substrate with a grid of them with the new substrate, the idea being the cardboard will decompose overtime as roots grow through it, etc., and it would be almost the same as if I replaced the entire substrate at once.

Is plain cardboard toxic to fish? (plain, as in, no ink on it)

 

[Yo_Loach]

No man, cardboard isnt toxic to fish per say, but it will rot/decompose/turn to dust over time in your tank, it will make you water cloudy and you fish not to happy.

Try using panty hose filled with sand around the roots and tying them at the end with a rubber band for planters. Or you can take a look at some gravel-ess planted tanks and see what they use for planters. hope that helps

hope that helps.