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GH & KH question

1812 Views 7 Replies 5 Participants Last post by  Aquaticco
Hi Everyone,

New to your boards and just set up a 46-gallon bow front tank. It's been cycling for about 6-weeks now and appears to be stable. I have a 3" Flourite base and run C02 with a PH of between 6-7

My question is this, my KH=1 and my GH=17 can someone tell me if this is good or not. I'm also looking for a good book on how to care for a planted aquarium, can anyone recomend a good book.

Thanks for all the help

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Welcome to APC! It seems that you have a good set up and it wouldn't be an exageration to say that whatever you ask on this site will get answered better than any book :)

Your KH and GH:

Test kits
The first thing that you must do before anything else is to verify that your test kits indeed show actual numbers. It'll probably be a hassle for you to check the kits by preparing clean solutions with known concentrations of HCO3 (KH), Ca and Mg (GH). Maybe you can just make sure that your kits are not old and also to compare the kits to a pet shop results (you could take some of your water there and ask them to test it for KH and GH).

The KH is very low but I'd leave it where it is and not worry about it. Some people may say that such low KH may lead to what is known as "pH crash" - a sudden pH drop down to some very low number (3 or 2). This sudden change may cause death of fish and probably plants. However a pH crash seems to be more of a theoretical than an actual phenomenon - it seldom happens.

Now GH of 17 is way out of whack. You will be better off bringing it down to more sensible levels - 3 to 6 is great, but even 9 would be ok.

I wonder how did you end up with such high GH. The first thing that comes to mind is that something in your tank (it maybe a single rock) is releasing Calcium in the water. But that would bring the KH and pH up too and that is not the case.

GH is a measure of the Calcium and Magnesium concentrations in your water. You can have GH =17 from Ca only or GH=17 from Mg only. Or mainly from one or the other. Without a Calcium test kit you have no way of knowing which one of the two elements contriubtes to such high GH. The Mg concentration is not checked with a test kit but it's calculated by using the GH and the Calcium - try this calculator.

If you don't want to get involved in testing Calcium and calculations you could try a simpler but very much blind approach. Test your tap water and if it has a GH considerably less than 17 then just do a few big (50% or so) water changes. That way your GH will go down but you will still not know the amount of Ca and Mg which are important for plant growth.

Another thing that may want to do is to make sure you check the pH more precisely. pH of "6 -7" does not mean much, usually you want to know if it's 6.1 or 6.9 :)

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You may have bad test kits or out of date test kits. Have the LFS check your parameters and see what readings they get.

When injecting C02 you need to keep your KH level at a least 3, this will help keep your PH from going to low.
Thanks for the help. I actually do have a calcium test kit as I have kept reef tanks for years and currently have a 150 setup. I used just RO water when I set up the tank but on my last water change I did a 50% RO and 50% tap water. Guess I will go back to the RO. When I first tested with just the RO I had readings close to what you had mentioned.

As far as books, you're right I can't find many books on the subject. I have found a few but not many.

The test kits are brand new by aquarium pharmasuticals (sp?) not the best but I was hoping they would work. I will do a major water change tomorrow

The PH is 6.3 to 6.5. I use a Millwakee PH controller to controll the dossage and I have it shut down at night

new to planted tank

Hi Doug and welcome

looks like youre getting some sound advice here. Being kind of new to this I will throw in my two cents worth. As far as books go. I would just read the forums here packed with more information and experiences of many than I think any book can offer you (IMO). With respect to turning off your pH controller im assuming you are using pressurized CO2. If that is the case i wouldn't shut it down because your KH is relatively on the lower side of the scale so your pH may fluctuate considerable during the night. In a planted tank the ideal situation is balance so i would just keep it on all the time and let it do its stuff.

Good luck and come back often theres some good stuff here
Using RO water only is not good for planted tanks, it contains no nutrients. I would go with all tap water unless you have bad water or stay with RO/TAP mix.

Increase your KH using 1/2 teaspoon of baking soda per 10 gallons of tank water. This should raise your KH by 2 degrees, if not you can increase the amount daily until the desired KH is reached.

A couple of good books for the beginner are:
1) Plants for Your Aquarium by Wolfgang Gula
2) Aquarium Plants Manual by Ines Scheurmann
These book cost less than $10 each.
Hi Aquaticco,

you don't need any cycling in a planted aquarium. That's a fish only tank issue.
We use 100% RO water, then we add and control all the necessary minerals and nutrients. There is no need for tap water. With RO you can make any water you like, full control.
Plants don't care about KH. KH is there only as a buffer to have certain pH for the fish. You can also have zero KH and plants will still grow fine. pH won't go bellow 4.3 as this is the lowest CO2 can go. Most Tetras love it.

So as you can see there is more then one way to run planted aquariums.

Thanks everyone,

I forgot to say I'm using Seachem's equilibrium with the RO water to help add a mineral balance.

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