Fluctuating tap kH question

[Ketso]

First off, I still have no fish in my tank. Still growing out my plants but getting close.

My question today is about the kH of my tap water and the fact that it fluctuates. Over the last 2 months, my tap water (and thus my tank water) has fluctuated between 4 dkH and 2 dkh (where it is now). I have read here and there that kH changes are very stressful to fish. Which leads me to ask the following questions.

1) What course of action, if any, should I take to maintain a stable kH?
Was thinking that maybe I should adjust it to something higher than what the tap normally is. Say 6 dkH. In this manner, I would just need to adjust the tap water, regardless of its kH, to 6 prior to a water change. Make sense? It does to me, but what do I know.

2) What is too low of kH?
I've read that 2 dkH is too low for most fish. Is it?

 

[BrianNY]

I agree with you Ketso. Unless you get the KH up to 3 you'll suffer the dreaded pH crash.

Crushed coral works wonderfully to buffer the water. Just add a handful to the filter and it will gradually leach calcium carbonate into the water column.

 

[Ketso]

Thanks for the input Brian!

Here is my quandry though. Let's say, after adding crushed coral, I do a water change when my tap water is at 4 dkH. The coral will then raise the kH, for example only, up to 6dkH. The following week, the water company decides to adjust the tap water to 2 dkH. Now, when I do my weekly WC, I will end up dropping the kH just by adding tap water. See where I am going with this?

I think I need to set the tank at a certain dkH and then adjust the tap water prior to adding it to the tank. I would need to use buckets of dechlorinated tap water and add something to them to adjust the water to match the tank, again, prior to adding the water to the tank.

Am I thinking clearly on this? Am I worrying for no reason?

 

[BrianNY]

The question makes sense. You're worrying for no reason. You must remember that what you're trying to achieve is pH stability. The effects of a weekly pwc with a lower KH will be harmless to your fish.

The KH of my tap water is zero. I've used crushed coral to buffer the water for years. Keeping discus I change alot of water and haven't seen any effect when doing pwcs. However, without buffering the pH has dropped to as low as 4.

I also don't think it's possible to dial in a number and keep it there. All of the biological processes in an aquarium keep changing the water chemistry. That's one reason it's so important to do water changes.

 

[Ketso]

K. Thanks again.