Blyxa turning red

Could be lighting becasue high lights will bring out the red on some plants, in your case your Blyxa could be turning red becasue of your lighting.

My blyxa turned red in my 20g, so it had to be the high light since my nitrates weren't exactly low. 5.5wpg of PC's, just fyi.

definitely high light...the higher the light the more pink/red it becomes...looks cool!

I can say yes to that too.

I recently recieved a good portion, and the old yellow/green leafs melted and new red/green came instead. Got 4wpg

High light, Iron, and low nitrates could be factors of plants turning red. Depending on the specifications of your setup, it could be anyone of them or all three.

On the other hand, I think Blyxa japonica looks a lot better when it gains color rather than being just plain green.

i agree most of the plants im my nano are bright green its good to see some variety.

Agreed, from what I've experienced, high light caused the color change for me. As for the comment on the plain green - agreed - looks too much like dwarf sag - colored up much nicer!