Fraying fins... is it the BN pleco?

[bmblsad 2]

Hey all...I am a newbie fish keeper. I have an 3-4 inch oranda (purchased in May) who has been the picture of health until this week when I noticed his fins starting to fray. I don't know why or what to do. I have API aquarium salt but no meds - however, can easily get them today from LFS.  I also have a 5.5g tank that I could use as a hospital tank temporarily if needed though it seems really small.

Here are the answers to some key questions. 

PS - it's been a rough month; my MIL died 2 weeks ago after a brief illness so my fishkeeping habits have been unbalanced (feeding and lighting schedules off, water changes done hastily and off schedule, etc, throughout most of October)

What symptoms are you noticing, and when did the symptoms start?
Fins beginning to fray
3 days ago; progressing rapidly; thought I was imagining it at first.

How big is your tank?
29g planted with anubia, swords, 2 crypts, 2 morimo balls; sand substrate

How long has the tank been set up?
July; it was an upgrade from a 15g; moved cycled Fluval AQ70 filter from 15 to 29g. Heated to 74. Use airstone.

How many fish and what kinds of fish do you have in your tank?
1 oranda: Barney
1 BN pleco: P-Lucky
1 nirite: Luiz
1 mystery snail: Boris

Am I overstocked?

How often do you do water changes, and how much water at a time?
30-50% weekly; yesterday 50%; the week before 30%.

Have you cleaned or replaced anything in your filter?
Squeeze out filter sponges every week
Emptied and wiped down filter 2 weeks ago

What are your water parameters for Ammonia, Nitrite, Nitrate, and pH? (Please give numerical values; "fine", "good", "normal", etc are not readings and will make it difficult to help you. If you do not have a test kit please say so.)
I use API Master Test kit + API GH and KH liquid test solutions; following readings were prior to water change last night
pH: 8.4 (!) It has been a very stable 8.2 until about 4 weeks ago and then it moved up to 8.4 (I keep a spreadsheet)
Ammonia: 0.25 (usually 0)
Nitrite: 0
Nitrate: 30ish; color was somewhere between 20 and 40; nitrates have always hovered around 5-10 and then late September shot up to 30-40. We've had a lot of rain. I'm on a well. I live in an agricultural area where I'm sure lots of ferts are used on nearby fields. Could they be seeping down into the groundwater and into my well?  I tested the straight well water and the nitrates are now around 30 where they used to be 0.
GH: 4 drops
KH: 15 drops

What do your fish normally eat?
Switch it up a lot. I may feed 6 omega one goldfish pellets soaked in tank water in AM and then some frozen brine shrimp or blood worms in PM. Sometimes I feed pellets AM and PM. I usually have kale/spinach/lettuce hanging from a clip, and a slice of zucchini and/or carrot. I've just started rotating rapashy gel food into the mix.
I fast them every Friday and then feed peas on Saturday AM that have been blanched in tank water.

Have you added anything (water conditioner, medication, algae chemicals, etc) to the tank?
When I do water changes, I add a large drop of prime and about a quarter cap of Stress Coat to a 5g bucket and then I add an airstone and let it degas overnight. I add a heater so it's within 1 degree of the tank temp before adding the new water.

I am on a well with super hard water and lots of iron (will turn your hair orange). I started out in the spring using straight softened water (Kinetico) but my plants looked like crap. After consulting a few planted tank forums, in August I started using a 50/50 mix of well and softened water. At that time, the well water was 0.25 ammonia, 0 nitrites, 0 nitrates, 16 drops GH, 15 drops KH. When I first noticed the jump in nitrates in my tanks I tested the well water and realized nitrates had increased from 0 to 30ish so reduced the mix to roughly 70/30 softened to well water. The softened has no nitrates or ammonia.

So, I'm perplexed. I have 4 tanks total and am worried that Barney (my oranda) is like the canary in the coal mine. My other worry is that maybe the BN Pleco is stressing him out -- but I NEVER see any aggression of P-Lucky towards Barney except the one time Barney tried to take P-Lucky's green bean away. I dunno. Please Help. Love my fishies and snails.

Should I pull Barney out and put him in the 5.5g? Pull out the Pleco and put him in the 5.5 temporarily? Or, use this as an excuse to upgrade to a 55g tank? I have abundant filters, heaters, etc. Just tell me what to do. Hope the pics help.

[koko 14,339]

Can you do me a favor? Take a full tank shot so I can see it better  You are slightly over stocked. I personally wouldn't have the BN in there right now till you can figure out this fin issue.

Also stop feeding the gel food for now. That food sometimes gets into the filter and will bud up gunk in there. Then that gets into your water and somtimes causes issues like this. So lets just feed pellets in the AM and frozen in the night. Don't let food hang around all day. This causes nitrates and maybe bacterial problems too.