Moving to Low Hardness -- How Should I Manage?

TPIRman

TPIRman

Fishkeeping Yellow Belt
Mar 5, 2004
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New York, NY
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Hi all --

I'll be making a move in a month or so, and the house where I'm going has well water. I sent samples to the state to be tested recently, and the results showed some very soft water:

GH: 37.6 ppm
pH: 6.4

There was no separate test for alkalinity, but with a GH of about 2 degrees, the KH would obviously be quite low as well.

I plan to put coral rubble into my canister filter to get things up to a safer level, especially because I'd like to inject CO2 eventually for the plants. How should I handle water changes? I got a Python to avoid the bucket brigade, but given the difference between tap and tank water that will result from using the coral rubble, I'm worried about pH swings if I just put the tap water straight into the tank.

The water at my current location is pretty soft, too, but I only have a 10 gallon, so what I've been doing is tossing about 1/4 teaspoon of baking soda into the new water during my weekly water change (experimented to find the right amount) to match the crushed-coral-hardened tank water. Easy enough, but I'll have a bigger tank at the new place, so I'd really prefer to use the Python.

So a couple questions:

- Where can I get coral rubble? I read in some archived threads that crushed coral can gum up the works in a canister, but none of the LFS in my area have the coarser coral rubble.

- Would it be possible to dissolve the appropriate amount of baking soda into a cup of water prior to a water change, and then pour this solution in slowly as the Python refills the tank? Or should I use a "reservoir" system and treat the water beforehand? (And in the latter case, what's an easy way to get the reservoir water into the tank? A pump? Powerhead? I'm clueless here. :rolleyes: )

Thanks in advance for any advice you might have.
 
I make my own Rift Lake mix to harden and buffer my soft water. I make a mixture of 5 lbs of epsom salts and 4 pounds of baking soda. After mixing, I add one tablespoon per 10 gallons of new water. Since baking soda gets expended fairly quickly, I also add a tablespoon of a carbonate - I use AragaMilk - per 40 gallons of water. This gives me hard, well-buffered water for my Rift Lake fish.

You probably will want to alter this (esp. proportion of epsom salts to baking soda) to meet your own GH and KH needs, but this should be enough to give you a start.

HTH,
Jim
 
Thanks for the reply, Jim! I've never heard of AragaMilk. You think that might be a preferable way to pad my water's KH a bit?

I'm mainly concerned with raising the KH to safe levels, especially since I want to use CO2 down the road. GH shouldn't be too much of an issue with my fish. But I'm struggling to figure out the logistics between the coral-hardened water and the soft tap water. If I had it my way, I'd be able to do the smart aquarist thing and just use what comes out of my tap. But it seems unsafe to do that with such a low KH (barely detectable with my home tests), so I'm trying to figure the safest way to raise the KH while keeping conditions steady for the fish during water changes. I'd also really like to know how to use a reservoir to age/treat tap water without resorting to buckets!

Thanks again--

-John
 
If you just want to bring KH up to levels where the pH will be stable (e.g., KH = 100-120 ppm), you can place some crushed coral in a filter bag or nylon stocking and plop it into your filter. The coral will dissolve and buffer the water. If it raises KH too much, you can reduce the amount in the bag. This method is nice because (a) it requires little or no thought once you get the right amount in there, (b) it leads to pretty stable water parameters, and (c) it's entirely natural and has minimal effect on pH. Unless you do massive water changes (50% or more), your KH/pH won't fluctuate that much due to water changes.

If you want to really jack up KH (e.g., for Rift Lake cichlids) then addtives are really the most reliable method.

What are you shooting for in terms of pH, KH and GH? What fish will you be keeping?

Jim
 
Hi Jim,

I am indeed just trying to get KH up to a safe level. I currently use the crushed-coral-in-a-stocking method in my HOT filter. However, I've read in threads such as this one such as this one that crushed coral isn't a good idea for a canister filter. That's why I'm trying to find a source for coral rubble.

If it wouldn't be unsafe to put the low-KH tap water into the tank during a weekly water change, I think I will just go with that. I like to do 35-40% changes weekly -- you think I'll be all right?

I agree that the coral method is so easy! And it has worked quite well in a little 10G at my current location.

Thanks so much for your help -- I really do appreciate it. I would be lost setting up this tank if it weren't for the online experts I've met.

Edit: Forgot to include the fish that will be in there: danios, corys, otos, and a dwarf gourami. Nothing too particular about hardness or pH, AFAIK, so I'm not shooting for anything in particular on those counts.

-John
 
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Hi John,

The crushed-coral-in-a-bag method is only a concern if you plan to run your canister as a bio-only filter. When canisters are set up as bio-only, the assumption is that they'll be opened for maintenance very rarely. This isn't true, of course, for conventionally packed canisters, which must be opened and cleaned at regular intervals. In this latter case, there isn't a worry about the filter bag collecting debris, because it can be rinsed when the filter is opened for cleaning.

The only downside for using a coral-bag in a conventional canister filter is that you'll have to open the canister to adjust the amount of coral in the bag (which allows you to set KH levels). Even this isn't much of a problem, because the coral dissolves pretty slowly, giving you plenty of time to open the canister and adjust how much coral you have in there.

How big is the tank the canister will filter? If we knew that, we could probably give you an idea of how much coral to start with.

Good luck,
Jim
 
Hey guys,
Just wanted to add a little anecdotal evidence. I use the crushed coral method, HOB filter though...

Halifax has soft water, KH around 30 or 40. With the coral in bag I get a pretty stable KH around 100-120 and my pH is pretty stable as well, the occasional fluctuation of 0.2. Although I think that I may have solved that problem as well, but that's another story with CO2 injection...

Anyway, yeah, coral in a bag is all good, but the bag definitely needs a rinsing at least every 2 weeks in my experience. This is a 10g, planted. Stocking is 3 swordtails, 2 albino cories and 6 MTS'.
 
Perhaps you could add a small HOB filter to the tank just for running crushed coral. Not ideal for a CO2 injected tank but definatley better than taking the canister apart all the time.
 
Hi all --

The tank is a 30G, and it'll be filtered by an Eheim 2213 with a FilterMax III pre-filter. I use two tablespoons of crushed coral on my 10G now, so I was thinking of starting with six tablespoons and going from there.

Also, to double-check, you all think I'll be fine with 40% changes straight from the tap?

Thanks again,
John
 
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