Part of that statement is dump the Scat WHEN the problem is solved AND you have the root nutrient issue resolved.
i hope by "dump" you meant returning to the LFS...
ignoring the fact that Scat are brackish fish, i do not recommend buying fish just to "solve a problem", but if you do go that route i belive that siamese algae eaters will also eat BBA and do not need the brackish conditions. you could go this route, but i is not the way i would go..
its not very high wattage i have 2 10 watt PC light bulbs, i dont dose ferts..ammonia is at 0, nitrite at 0, nitrate at 10,ph at 7.0 .....as of phosphate,GH, and KH i have no idea...Also dont use Co2, i would it isnt very bad but its spreding quick...
ok well...
you are at a pretty low light so your probably do not need CO2, though if you wanted to dose Excel, i do not think it would hurt, probably would help slow down the spread of the bba, you can usually dose 2x the recommended dose safely, for short periods of time, i would not exceed 3 days like this, if you choose to try it.
ok test results...
NO3, is a little low, but at the light level some is better then nothing. unfortunately, hobby grade test kits are very inaccurate, and the "real" level may in fact be 0 ppm. :? if you are not already using a drop into a test tube style test kit i would recommend getting one, also if you can i would suggest taking a sample into you LFS and see if you can get a second opinion. if it is in fact 0 you will need to start dosing NO3.
PO4 is another nutrient essential for plants. you do not have a test kit, so i would highly recommend picking one up next time your at the LFS (soon if possibly) you should have some PO4 (like 0.5-1.5 ppm is good) if you have 0ppm you will need to dose.
i would also suggest you pick up a KH/GH test kit and try to give use those #s.
if you end up starting to dose NO3 and PO4
(this depends totaly one your tests) you may need to start dosing K, since K helps in the uptake of NO3 and PO4 and is also needed by the plants.
at the least i would suggest starting to dose a basic trace mix, like Flourish Comprehensive, with your PWC.
i think if we can trace down what is out of wack we can stop the BBA in its track and make sure it never comes back
HTH