Potting Soil

[Crazybob]

Hello all,

Im VERY slowly designing and building a new tank and I keep going back and forth on what I want to house. That being said, I'm thinking of doing some smaller fish (community based in appistos) with some plants. I was thinking about using sand or a very fine gravel but I saw someone post that they put soil under that for plants. Is there any reason you can't just use pitying soil for the whole substrate?

 

[OldMan47]

Cheap potting soil makes a nice substrate for plants under gravel or coarse sand but it will fill the tank's water with floating bits if you don't put a cap over it. I use coarse sand for the cap.

A recent trick I learned for potting soil is to use a shallow plastic container to hold the potting soil. That way, when you need to replace the substrate after a few years, it will be easier to remove it. The potting soil becomes a smelly mess to remove when it has been in place for a few years and you want it to be easy to remove.

 

[AbbeysDad]

Generally speaking, potting soil contains a fair amount of organic material. (e.g. perlite, vermiculite, peat moss...) and some of these elements will want to float. Also, the high level of organics deep in a substrate can create problems if/when anaerobic bacteria are involved in decomposition (creating some ugly gases like hydrogen sulfide).
A better approach is to use top soil instead of potting soil...and better still is mineralized top soil that has had the organics 'burned' off. This is placed in the aquarium first at 1-2", then a fine gravel or sand layer of 1" or so is used to cap it. Care must be taken not to stir the substrate too much when planting. The following link may have value for you:
Mineralized top soil

Note: Without some soil in the substrate for plants, you'll be doing the equivalent of hydroponics (hydroaquaponics?) and will need routine fertilizer doses. A bed with a soil base, some MTS's and California Black Worms and now your into organic aquaculture.
Subnote: Many people are very successful with plants in an all sand substrate using ferts. I think the soil base substrate prolly grows plants better, but it is more involved to setup and establish.

 

[Crazybob]

Cool thanks for all the info guys. Will the top soil help promote algae growth if I don't have a lot of plants in the tank?

 

[AbbeysDad]

Cool thanks for all the info guys. Will the top soil help promote algae growth if I don't have a lot of plants in the tank?

Perhaps more than sterile sand, but less than potting soil. If you setup a soil tank, you'll likely want a week or more with several water changes - I'd have lighting at a minimum or off during this period.