Ph, KH, stocking, etc. ?s SSL

[current516]

Hello all. Another Newbie. Sorry for so many questions at once.

So...I am thinking of buying some Discus.

I have a 60g, 24" tall, High Light, CO2 injected, heavily planted tank (Amazon Swords and many more). I have 6 Cardinal Tetras, 1 German Blue Ram, 1 Gold Nugget Pleco, 2 Siamese Algae Eaters, 4 Ottocinclus, and 1 yo-yo loach. PH= 6.8-7.2, KH=9, 50% WC weekly

My questions:

PH- Because I inject CO2 my Ph ranges from 7.2 to 6.8. Is this "stable" enough? I always hear about stable Ph. Does that mean no change at all? How much change is acceptable? Do I need to get a PH controller? Also, is my PH range low enough for discus?

KH=9 Too high? Do I need to get RO?

I plan on starting with about 4 Discus. Do I need to buy them all at once? Are any of my fish going to be big problems?

THANKS!

[FishLover]

I'm no expert. Here is what I think:

No more than .3 pH swings within 24 hours.

I'm not sure if you Siames Algae Eaters are Chinese Algae eaters or not. Most shops confuse these two. The Chinese Algae Eaters are no no for Discus. I would take them out.

I don't like Plecos in my Discus tank for two reasons. 1 They get too big. 2 they may suck on hte side of Discus and kill them.

Not sure about yo-yo loach. Never had them before.

Your other fish are OK. I would buy all 4 of the at the same time. Keep in mind that they may fight all the time if there is not enough number of them in the tank. At least 6 of them would be better. Your tank is big enough for 6 of them if you take out the pleco, Siamese/Chinese algae eaters and the loach. Cardinals, ram and ottos don't have big bio load so your 10 g per adult discus should be OK, especially if you have some plants to help you with the nitrate removal.
Weekly 50% WC is fine as long as you do wnt to breed them or feed them with lot of BH.