Hardness Question

[kush]

My city seems to be tinkering with their water recently. I'm just barely testing one degree of KH and I'm not reading any GH at all - in the past I've been getting between 2 and 4 both dKH and dGH. I've got juveniles in a 55 gallon tank and two questions: what should I be targeting for hardness and and what's the most expeditious way of getting there? I can put crushed coral in my canister but then when/if my tap goes back to 4dKH I'd just have to take it out. Can I / should I use canned cichlid buffer (Seachem, I think?)? I have a bottle of unused Kent Discus Essential lying around somewhere - is that irrelevant? TIA!
-Kerry

[David Rose]

Hi Kerry,

I had posed this question to Paul/pcsb23 one of our moderators. He was very kind to respond with the following recommendations:

Adults/Sub-adults & Juvies
PH 4 to 8.5 ideal being 5.5 to 6.8
GH 0 to 20 DH ideal being 2 to 6 DH
KH as above.

IMO, the concern with KH less than 4 is the possibility of PH crash, so a buffer of some sort would be advisable.

I hope this helps!

[kush]

Thanks David.

So, we're thinking the need for hardness is to buffer pH rather than having some general physiological relevance for the fish themselves?

My pH out of the tap is dead-on neutral which is the municipal's published target. pH in the tank is typically in the neighborhood of 6.8 and, although those shades of green get a little hard to differentiate as you go down the scale, I think I'm at about 6.6 now and holding. Obviously, I'm watching it closely.

I'm a high-tech planted tank guy from way back so I thought I knew my chemistry. But these are my first discus and I have them in a BB tank with just a couple of potted plants and its a whole different laboratory!

I guess I'll stop at the LFS this afternoon and read the label on a can of cichlid buffer.

[David Rose]

There are different schools of thought on this and it varys depending on the age of your discus. The carbonate (KH) is important to buffer or stablize your PH level. The Calcium/Magnesium and other mineral content can be important for juvenille development. Some believe that our discus can get this totally from a good and varied diet.

In the end, I think that if your PH is stable you don't need additives. I would use something more natural like the crushed coral or possibly baking soda for the PH rather than other additives such as Discus Buffer or Kent's RO Right. Others may jump in and offer some good recommendations as well.

[kush]

I went to the LFS and read the labels for chemistry-this and buffer-that and none of them, frankly, seemed like a particularly good idea and, while I was standing there looking at bags of crushed coral I was thinking, 'carbonate... bicarbonate... OH, YEAH! baking soda'! Then I saw your reply re: same. So, I found some old notes with the formula for increasing dKH with baking soda and I'll just try raising KH by a half a degree with every water change for a few days and keep on testing.

I bought a bag of crushed coral but, other than putting it in a bag in the filter, I'm not sure how to go about using it - but I'm sure I'll find someone's notes on it around here somewhere.

Thanks again.

[David Rose]

You may find the following thread helpful; especially, post #3:

http://forum.simplydiscus.com/showthread.php?t=71655&highlight=baking+soda