Potting Soil For Aquarium

hi! I researched this topic and realized it should be okay to use 100% organic soil for the bottom substrate of a planted tank. I picked some up yesterday but had a complete brain fart and I realize now that it also contains fertilizer. However it does say 100% organic. Would this still be ok? Or would the fertilizer be harmful? Thanks!

 

I have an outdoor 29 with organic soil that is capped with pool filter sand. I have no inhabitants in it so this is probably not much help. As i've not tested the water at all since its been set up about 1-2 months ago. My personal experience with it is its messy and when it cools off and it comes time to b ring the 29 in I will be emptying everything out of it and go with my go to pool filter sand a Fluval 206 or 306 a school of Tiger Barbs and a school of KhulI loaches

 

Years ago I had a 75 gallon tank in which I used organic soil topped with fine gravel. That soil did have fertilizer in it and I had no issues at all - I remember having a bit more algae in that tank than the others, but that could have been due to any number of things (other than the soil).

I'm not an expert on this, so just relating my experience...

 

Thank you for the replies! I think I might try it out. I just hope it doesn’t spike the ammonia.

 

My large tank has organic potting soil capped with pool filter sand. It has worked reasonably well but I do have elevated Nitrates in the region of 10 - 20 ppm. I kind of hope/expect this will stop as the root feeding plants use up the (natural) fertilizer. As far as I remember I also had elevated Ammonia at the beginning but It had it running for 1 - 1½ months before adding fish and it was either gone by then or processed by the biological filter - and could be the reason for the elevated Nitrates.....

Maybe the fertilizer in your organic soil is manure of some kind?

I mainly went down that route due to cost. In my smaller tank I went with Amazonia Aquasoil (un-capped) and it is clearly the superior substrate of the two but I quite like the pool sand top substrate of the big tank. Just planted some big Swords two weeks ago and they seem to absolutely love having their roots in the potting soil.

I would say give it a go and test your water. Also be careful in the future not to mess up the substrate as the lighter potting soil naturally will surface if given a chance.

 

My large tank has organic potting soil capped with pool filter sand. It has worked reasonably well but I do have elevated Nitrates in the region of 10 - 20 ppm. I kind of hope/expect this will stop as the root feeding plants use up the (natural) fertilizer. As far as I remember I also had elevated Ammonia at the beginning but It had it running for 1 - 1½ months before adding fish and it was either gone by then or processed by the biological filter - and could be the reason for the elevated Nitrates.....

Maybe the fertilizer in your organic soil is manure of some kind?

I mainly went down that route due to cost. In my smaller tank I went with Amazonia Aquasoil (un-capped) and it is clearly the superior substrate of the two but I quite like the pool sand top substrate of the big tank. Just planted some big Swords two weeks ago and they seem to absolutely love having their roots in the potting soil.

I would say give it a go and test your water. Also be careful in the future not to mess up the substrate as the lighter potting soil naturally will surface if given a chance.

Thank you for sharing your experience, that’s good to know. I believe it has earthworm castings as fertilizer. But it also has those white balls (not sure what they are) that are often found in potting soil. Should I sift them out? I would also cap with some sand as to help avoid the mess lol

 

The white "balls" if small and granular kind of size are likely to be perlite which is volcanic glass. When used as an amendment it has high permeability / low water retention and helps prevent soil compaction. In that case you should leave it in. Have a read here:
Perlite - Wikipedia

In terms of capping with sand, yes that is absolutely a must. When I mess around in my Amazonia Aqua soil it settles quickly again without a sand cap whereas messing with the potting soil, like uprooting a big sword creates an absolute mess, only barely controllable due to the pool filter sand cap.

 

The white "balls" if small and granular kind of size are likely to be perlite which is volcanic glass. When used as an amendment it has high permeability / low water retention and helps prevent soil compaction. In that case you should leave it in. Have a read here:
Perlite - Wikipedia

In terms of capping with sand, yes that is absolutely a must. When I mess around in my Amazonia Aqua soil it settles quickly again without a sand cap whereas messing with the potting soil, like uprooting a big sword creates an absolute mess, only barely controllable due to the pool filter sand cap.

Thank you so much!! Quick question, do you then sift through the sand when doing a water change or do you just leave it be to avoid a mess?

 

I vacuum the sand every 2 - 3 WC's. It doesn't disturb the potting soil unless you go too deep. In other words I make sure only to vacuum the sand.

 

I vacuum the sand every 2 - 3 WC's. It doesn't disturb the potting soil unless you go too deep. In other words I make sure only to vacuum the sand.

Thank you for all the information! One last question, did u rinse the soil before adding it?

 

No I didn't. It becomes mud if you try to rinse it and it also think it kind of defeats the purpose in the end,,,,I mean it is supposed to hold nutrients in various organic forms and what if left if you rinse it down "sand"? Also I needed many many pounds so it was too much of tasks to even sift it to get rid of bigger pieces of wood etc, however I think sifting it to remove bigger pieces may be useful but not mandatory.

I did rinse the capping sand carefully though and also went for a slightly bigger cap around 2". The water was only a little cloudy for 1 - 2 days so no real problem. The key is the sand cap. Do water the soil carefully though before you add the sand to avoid air pockets, but stop before it becomes mud.