Discus And R/o

[elmo666]

I'm an avid discus keeper, and tho may knowledge is limited I strive to do things right. Tbh I looked into all things quite deeply, but then find myself confused by all the often conflicting advice/opinion.
I have a 250ltr corner tank, fully planted, co2, eheim pro 3 external and surface skimmer. Water changes are normally done with 100% ro with pro discus mineral used to correct it. Temp is 84, ph6.5, and I use a drop tester to keep an eye on things daily. Now, most of the time things are fine, but occasionally I see rapid gill movement and my rams and some discus hanging at the top. The only way I can seem to alleviate this is to adjust the spray bar for more surface agitation, which I know drives off my co2. Can't get to the bottom of it. I have previously seen quite high nitrate readings, so I put on a nitrate filter using seachem denitrate, but a friend at my lfs talked me in to taking it off saying it was pointless whilst I dose with ferts. So, here are my questions:
1. Is 100% corrected r/o a good idea for discus, I have a three stage cbr filter, would I be better off using a mix?
2. Nitrate filter or not?
3. Possible causes of oxygen shortage or other reason for fish hanging at the top.
I'd like to get things right ad I'm currently maturing a new 300ltr tank which is fully planted with aqua gro soil, just waiting for ammonia spike to come and go. I'm seriously considering returning the nitrate filter to this set up.
thanks

 

[wrighty8529]

hi are you using co2 bottle or air pump if just co2 injected then add a air pump also how often are you doing water changes?

 

[elmo666]

I use co2 with the diffuser positioned so that 80% is taken into the uplift to the filter, to maximize absorption, increasing the contact time. I have a 1000 lph circulating pump just above the substrate to ensure good circulation through the lower levels and a surface skimmer to remove any surface films that may be present. My spray bar is at the water level, aimed against the glass to "bounce" a nice gentle ripple across the surface. I change 50 litres twice weekly. I've not seen the need for an air pump as there is lds of water movement and surface agitation. After all, no matter how much air you pump in, its only the surface disturbance that aids oxygenation.

 

[wrighty8529]

dose there gill movement go fast when u go near tank or when u ant near it as can be stress also how meny discus u got in with um?

 

[elmo666]

There are 6 discus. The other occupants are 4 clown loach, 8 dwarf coryadoras, 8 black phantom tetra, 4 rams and a snowflake plec. I notice the laboured breathing / hanging at the top from my armchair. To be honest not noticed if it increases when I approach as the discus rush forward thinking its feeding time and "patrol" the front of the tank watching my every move......so know, guess this doesn't stress them at all.