still kind of confused with the whole KH / GH / TDS

[totalnewb]

So I have cardinal tetras and leopard danios. I have read that cardinals prefer a really low ph. and generally low tds. I use RO water exclusively as my tap ph is off the charts and contains a fair amt of ammonia. I have to doctor the RO water.
Right now my ph is about 6.7.
tds 150ppm
kh & gh both 3 drops ish.

After using RO rite, ans some seachem for the plants, the water I am looking to introduce today is ph 6.5, tds 80, kh&gh almost nil.

I am under the impression that the tds of 150 is too high..? So am looking to lower it gradually over several changes so as not to shock the fishes. I have read so many different things at this point, can anyone tell me where the numbers are supposed to be?

what to do about low levels of kh and gh? cardinals want it soft, but still need enough to be stable and keep ph stable...?...

am a bit unclear on the tds / gh / kh relationship. if gh and kh determine "softness" what when they are low but the tds high?

and what about the danios? I am under the impression that they will adapt..?
i am quite confused.

 

[Rivercats]

You really don't need to go to all that trouble as fish will adapt to most tank PH/GH/KH and honestly most people don't even know about TDS. I have angels, rummynose and cardinal tetras (25 of each), and rams in a 220g. It's heavily planted and I do weekly 50% WC's. I keep my GH and KH at 4 which is high enough to keep my PH stable. My PH is usually around 7.0. My angels and rams spawn and some of my older rummynose females are looking like they might have eggs. If you try to keep your tank at specific standards like you want you are going to drive yourself crazy! Also when PH drops to 6.5 the BB will start slowing down. If the PH drops to 6.0 or below BB stops working. Since you use all RO you might want to add alittle bit more of your reconstituting powder to up the GH and KH.

 

[totalnewb]

thank you!
wow. what a beautiful tank. must have taken a lot of patience.
I really appreciate the feedback. There is so much to absorb when you engage a new science / hobby. based on what I've taken from your post, I will focus mainly on keeping a stable kh and monitor behavior.
I did a 35% - 40% water change this aft with the water that i described earlier. it resulted in a tds of 120, a ph of 6.6, gh of 4, kh of 1!!!!
any suggestions?


btw thanks again.
TN

 

[Rivercats]

Thanks my tank is a work in progress!

I've never used RO right but if you add more won't it raise your Kh/Gh. Your Kh needs to be at least a 4, which is what my tank runs at, in order for there to be enough buffers in the water to keep the ph stable. Also if your ph drops to 6.5 your BB will start slowing down, if ph drops to 6.0 your BB will stop working. Keeping your Kh at 4 or higher will keep you ph from dropping too low. You need to keep you eye on your ph also. So IMO you just need to use more RO right to up your levels alittle.