Sick German Blue Ram And Reticulate Loach

[FishParent]

Help! My German Blue Ram and my yoyo loach are both lying on the floor of my tank breathing heavily, being listless/not really moving, and looking generally sad

I suspect the cause is a pH burn; I checked the ammonia and the levels were at ~ 0ppm, but my pH was way, way, way too high (beyond the scale of my testing kit).
I've since brought it down as slowly as I could through water changes and it's now back to the levels that I normally keep it at, but I'm wondering whether there's anything I should be doing to help my fish

Also wondering if it could be anything else.
If I can work out how to upload a photo, I will add one of him looking sad!

So far I've added extra aquarium salt and a product called 'Stress Coat'...

Thank you for any wisdom/advice!

 

[FishParent]

My sick German Blue Ram:

 

[FishParent]

Oops, I just read the guidelines. More information:

Tank size: 130L

pH: Usually between 6.6 to 6.8

ammonia: 0ppm

nitrite: ?

nitrate: ?

kH: ?

gH: ?

tank temp: 26-29 degrees Celcius

Fish Symptoms Both fish are sitting on the floor and leaning on things or listing to the side, breathing heavily, being listless/not moving

Volume and Frequency of water changes: Approx 1/5 of the tank weekly

Chemical Additives or Media in your tank: Carbon for plants, 'Stress Coat' because I thought it might help the sick fish, aquarium salt (same) and tap water conditioner

Tank inhabitants: red rainbowfish, neon rainbowfish, German blue rams, reticulate loaches, dwarf otocinclus catfish, cherry barbs

Recent additions to your tank (living or decoration): None recently. Most recent probably a planted piece of driftwood

Tank Age (How long the tank has been up and running): Many months, 6-8?

Recent Events in the tank (things such as algea blooms, illnesses.. etc.. that have been treated recently): Having issues with hair algae and green algae that I haven't resolved yet, and upon discovering my sickly German Blue Ram this morning testing revealed pH to be too high (beyond scale of testing kit), but this has since been brought back to normal levels as slowly as possible. Other than that, nothing recent that I know of.

The type and size of your filtration: Not sure of size/rate, it's a pump?

Not a great photo, but my sickly reticulate loach: