yep. i did a 50% a week ago as you were right as the nitrates were sky high. I then did nothing and jut waited and kept testing.
I also got a nitrate dipstick to keep me same to see how high and it showed it dropping and then one morning ..down and gone. I didnt believe as i must have done loads of nitrite and nitrate to double check.
I then did a few days of putting in ammonia (4ppm) and watch it convert to nitrate. The seneye is a great way as it tests every 30mins for nh3 so i could see it going down.
So far i put in 6x zebra danios, 6 white cloud minnow, 12 neon tetras and 6 harlequin rasbora.
I will wait for a week and then prob add 3x pearl gourami and then others 6 dwarf rainbow fish, 3 molly. 3 platy and 2/3 oto - one school per week etc
ta for the advice on the lfs.