Water tests and water change today. All looking good, our naturally high pH is coming down too (now at about 7.4) so thats something. Added 5 MTS and they went under the sand immediately lol, so I think they are happy. Plants are growing too!! Photo to come.
We lost two of the other betta at work so I'm wondering if there was something amiss even when I bought him home. Will wait and see what we get in next batch and go from there.
As an aside, are there any other options for a 5.5g aside from a betta? Bearing in mind again that we can't get shrimp.