General Hardness & Carbonate Hardness?

[Knife]

I've had my 65gallon, moderately planted tank set up for about.. 2 months, cycled it and recently added some albino corys and some Rosy reds.

PH is 7, Ammonia is 0, Nitrites are 0 and I'm doing a 30% water change tomorrow to lower the Nitrates which are around 20 (doesn't seem to bother the fish, but will get it to 0 as well)

One thing that is gotten my attention is that my water tests indicate that my General hardness is sitting at 180ppm.. now, is that something that I should be worried about? or should I not sweat it? Also, my Carbonate Hardness is 40ppm, should I be concerned?

Correct me if I'm wrong, but is the Hardness of the water only a pain if you need to change the ph?

 

[jb1997mcd]

Hey Knife,

A couple of things. Nitrates are the end result of the nitrification cycle. Almost all cycled tanks will have nitrates in them. Everything you read says they should be kept under 50ppm, however, a lot of folks recommend keeping them under 30ppm. Plants can help a bit, but water changes provide the best results provided the water you add does not already contain nitrates.

I don't think you need to worry about your GH at 180ppm or estimated 10dh ( 180/17.9). Your water is a bit on the hard side.

Carobonate hardness or KH acts as a buffer to acids in your tank. The lower the kh the less acids your tank can handle and eventually the ph can start to drop. You can monitor your ph and kh to see if you notice any changes. If you are doing weekly water changes and not overstocking your tank I don't think you will have any problems. Kh = to about 2.2dh at 40ppm.

The higher the carbonate hardness the harder to change the ph. It is typical to find higher GH and KH in higher PH waters.

You may get some other opinions.

jb

 

[Essjay]

What is the nitrate level in your tapwater? That is the lowest you can get it by water changes. The general guide is to keep the nitrate level from going above the tapwater level + 20. In the UK, the legal limit for nitrate in tapwater is 50ppm; it is not uncommon here to have levels of 40ppm. Fishkeepers with this tapwater nitrate, for example, should keep their tank nitrate below 60.


Your GH is middling. It should be fine for most fish, just avoid those that like it very soft or very hard.

KH (carbonate hardness) is the one that affects the ability to change pH as carbonate 'soaks up' acids. If there is a lot of it, it resists changes to pH. But yours is low, you have the opposite problem. You don't have very much carbonate so it will be used up quickly meaning you are at risk of the pH dropping. I'm not saying it will drop, just that it will be easier for it to happen in your tank. I would keep a close eye on your pH especially towards water change day. You may find it beneficial to two or even three small water changes a week rather than a larger one once a week. That would help keep your KH topped up.
If you do have problems with your pH you could try adding a bag of crushed coral to your filter. This would increase your KH slightly but also increase your GH and pH. The increase would only be small, so it shouldn't affect your fish. To give you an idea, I left a tub of water with crushed coral in the bottom to stand to see what it did, and also a second tub of just water for comaprison. Not terribly scientific, but it gives a rough idea. After a week, the GH and KH in the tub with coral were both 2 degrees (about 35ppm) higher than the tub without coral, and the pH was 0.2 higher.

 

[Knife]

I tested my tap water and it came up as 0 Ammonia, 0 Nitrite, and 0 Nitrate, also the ph is 7.5 while the KH is 40, GH is 180 as well.

So to my understanding I should say.. do two, smaller water changes rather than one big one? I do keep a close eye on my ph, and I watch my fish closely to watch their behavior, they seem happy and healthy; I believe I have also caught glimpses of my minnows trying to spawn didn't think they were old enough..

 

[Essjay]

If your tapwater nitrate is zero, your aim is to keep the tank level at or below 20. It will be highest just before a water change.

Can I suggest you leave a glass of tapwater to stand overnight then test the pH again. The pH of tapwater commonly changes on standing, usually up but sometimes down. If the water that's stood also shows a pH higher than the tank, it does indicate that the tank pH is falling. Nitrate is acidic as are a lot of things secreted by the fish. Two small water changes a week will remove some of these acidic things as well as topping up the KH. So, for instance, instead of doing one 20% water change, do two 10% changes. So long as the two smaller changes keep the nitrates down to at or below 20, you'll be doing enough.

 

[Knife]

Okay, I'll leave a glass of tap water to stand for a day and I'll test it tomorrow; the two changes a week should be easier for me to do anyways, less pails of water for me to carry up and down stairs at a time lol.