failure to thrive

[sea gnome]

I dose with kalk about once a week as I don't have a Ca reactor. The point about dissolved O2 in tank is a good one, one of my chem lab experiments this year (a month ago) was to measure the O2 conc. in seawater and I used the water out of the tank, the results were not low. I have had a small cyano algea problem which had almost dissappeared but is starting again. I went and got some carbon to run as well as liquid marine buffer to raise pH as well as some trace elements to try, Still having losses but maybe it will turn around soon. Tommorrow I am doing another h2o change. Will post again with results. thanks for all the suggestions. Rachel