Water hardness question

[Biotoper]

I'm starting my first aquarium, and I'm trying to get an idea of how good my tapwater is (I'm in the Boston, MA area, off the MWRA water system). I dowloaded some of the detailed monthly water quality analyses that are available for my water supply, and I'm a bit confused by the hardness values given. I still need to go get a test kit (the Aquarium Pharmaceuticals Freshwater Master Test Kit sounds like a good all-around kit), so these values might differ from what's coming out of my tap, let alone what the values would be after circulating in my aquarium for a while. These data are taken from a shaft that supplies my town, post-treatment plant.

pH 9.3 (the treatment plant increases it from the reservoir's natural pH of 6.5 to reduce bacterial growth)
Alkalinity 40.2 mg/L (presumably this is KH. The reservoir has 2.5 mg/L)
Hardness 14.4 mg/L (presumably this is GH. The reservoir has 7.8 mg/L)

Assuming the conversion 1 dH=17.9 ppm=17.9 mg/L, that means the shaft has a KH of 2.2 dH and a GH of 0.8 dH! And the reservoir has a KH of 0.14 dH and a GH of 0.44 dH. Those numbers sound really soft to me, almost distilled water. And I've read that high pH and hard water generally go hand in hand, unlike what I'm seeing here. So are these numbers right, or is my conversion formula totally off?

Thanks for your help.

 

[amosf]

I'd get a test kit and try your tap water. Let it sit a while first. I can't imagine the pH would stay high for long if the kH is only 40ppm... As you say, if anything this water looks to be on the soft side...

 

[Biotoper]

Thanks - I will do that. So the pH will drop naturally while it's sitting around by taking up CO2 from the air?

The next question is what should I do about the softness? Everything I've read has said to acclimate your fish to your water quality rather than keep maintaining your water at the conditions your fish prefer. People seem to be really happy when they have soft water out of their tap, so I guess I'm lucky? However, I'm planning on adding a homemade CO2 system and I don't want pH swings, so should I increase the hardness somewhat? If so, how (adding baking soda?) and what is a good dH to shoot for?

 

[dimsem]

Hopefully Biotoper won't mind if I piggyback on his question, because I just came here to ask exactly the same thing. From my local water report:
Alkalinity: 29 mg/L
Calcium Hardness: 22 mg/L (Is this KH?)
Hardness: 42 mg/L (Is this GH? Or is GH 20 mg/L, 42- 22?)
Total solids: 98.5 mg/L

Any guidance about how to interpret these numbers, and about their implications for what sorts of fish are most appropriate for me, are appreciated.

 

[carpguy]

Biotoper,

Briefly, the MWRA are aggressively banging around your water supply for a bunch of reasons. I don't know all the details or all the chemistry behind it. Hopefully someone like HappyChem or RTR will come by and address some of it in detail.

What I can tell you is that they're using Chloramine to restrict bacteria, so you're going to want a dechlorinator that addresses Chloramine. I like Amquel, Prime is supposed to be good as well.

They're softening the water as well as increasing its pH. I think they're doing this with lime. It has to do with controlling mineral deposits and with reducing the amount of leaching of lead from old pipes. You wind up with soft high pH water. Where to go from here? Not a clue, personally. I did see that they're also tinkering with CO2 levels, so testing it after letting it sit overnight is a good idea.

You seem to be good with your research, so you may want to google a little harder along those lines.

I like Nutrafin's test kits. Started with AqPharm's master kit and got frustrated with it. Didn't trust the accuracy. Opinions will vary on this.

DemSem,

You've got soft water. Without a pH or a location its hard to say more.

HTH

 

[dimsem]

DemSem,
You've got soft water. Without a pH or a location its hard to say more.
HTH

I haven't measured my pH yet, but from my local water quality report it hovers between 7.1 and 7.5.

 

[RTR]

GH is calcium and magnesium hardness primarily. This is the factor pointed out when discussing whether fish are from "hard" or "soft" water. In captivity it really has little to do how well the fish do in tanks for maintenance, but it can be important for breeding certain fish.

KH in natural waters is also called hardness, but is also better called alkalinity, or sometimes carbonate hardness. This in tanks without added buffers the primary controller of pH and of the stability of pH. Utilities manipulate this to protect the pipes in the network and also in the houses served - soft acid water is hard on piping. Normal metabolism of fish and bacteria in tanks uses up some of the KH, buffer capacity, in the water. If the KH of the source water is low this can cause problems with stability of the pH.

KH, like GH, is reported as the equivalent of CaCO3 in ppm or mg/l, or as degrees with one degree being 17.86 ppm CaCO3. This does not mean that the mineral salt involved is only calcium carbonate, just that the measured water has the equivalent of that much CaCO3, whatever minerals are actually in it.

Tank operation is simpler IMHO & IME if KH is 3-4 degrees or higher, as the conditions are more stable.

 

[carpguy]

DimSem,
Your water is soft and your pH is more "normal" than Biotoper's. Its closer to what you'd expect to see with water that soft.

As RTR mentioned, the GH isn't all that especially important to the general health of the fish. It comes into play with some plants, with breeding certain fish, with snails, etc., but its not all that significant day to day.

KH is a measure of the water's ability to buffer acids and ideally you want to see it north of 3 degrees (about 50 ppm). This buffer will get used up over time and once it zeroes out you risk a pH crash, a sudden increase in acidity that can be harmful for your fish. (Kill them kind of harmful).

Regular water changes will help to recharge the buffer. Baking Soda can be used to add KH.

I also have very soft water and I like using a small mesh bag of crushed coral in my filter. This also adds KH, but it does it more slowly and continuously than Baking Soda. It dissolves slowly over time rather than all at once. Start with a teaspoon per 10g and monitor it until you get to where you want to be. Give it a few days to reach a stable level. You may need to add some or take some out.

 

[ArkyLady]

carpguy is right on. I wanted to add that I started using Seachem's onyx sand just because it claimed to help boost the kH and it does do a fine job in my experience. They have other substrates that make the same claim as well. So if a substrate change is an option for you, it's something else to consider.