[davemonkey]

I've seen people use Pothos Ivy and Spathiphyllum in hard-water/African Cichlid tanks. But they will not live submerged (not for long anyway). What I've seen is the roots dangled in the water column while the foliage is kept above the tank. Other than that, the only submerged plants I've seen in those types of tanks are the swords, anubias, and java ferns (which you have already tried.)

Maybe you could lower the water hardness and pH by removing that bottom layer of crushed coral? I know it sounds like a lot of work, but it might open up your plant options.

-Dave

 

[davemonkey]

Since you already have the tub, I say jump in and rip that bad-boy apart! :axe:

Put all the fish, plants, and as much water as you can in the tub. You can catch the fish easier if you take out most of the water first. When you do water changes every other day that your fish are in 'solitary', use your tap water and they will gradually adjust to the new pH.

Then, you will have a wonderful tank set up and ready for your new plants when they arrive!

-Dave