There are several types of bonsai soil, one is based on a fired red clay and the other is more of a volcanic pumice sort of thing. The former is Akadama and the latter is Kyodama. I have had good results in tanks using akadama. It is kind of like turface or sms, ie a fired clay. It has no big nutrients of its own but has good cec. I do not know which variety you are concerned about but a mix of the two may be better then akadama alone. I would cap it with a different substrate as it tends to packl down and fall apart in about 18-24 months. You may have some issues with cloudiness. There are many different brands, Ithink the one you are referring to is more likely to be Kyoto not Koyto. Do a google search on bonsai soil or akadama and aquarium and you will find some useful links.