Tropical Fish Keeping - Aquarium fish care and resources

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HollyinWA 02-16-2010 11:14 AM

KH/pH/C02 question
I bought a KH/GH test kit. I found a website that Natalie had posted that explains how to find out what the C02 level is. I tested my tap water, and if I did it right, my KH is 10. It said to count how many drops until it turns the water a certain color. I counted 10 drops....mixed in one at a time. When I looked at the directions it appears that whatever count it is that is what the KH is and then there is a conversion chart in the directions that shows that the number of drops of 10 equals the dKH of 10 which equals the ppm GH/KH of 179. When I tested the GH it ended up being the same amount of drops...10.

For my tap water, I looked on the chart on the site that Natalie posted and if my pH is 7.6 my C02 level is 7.5 and if my pH is 7.8 (at the worst) my C02 is 4.8. I did test my Ph out of the tap at it is between 7.4 and 7.8. I figure around 7.6/7.7....not right on 7.8....kind of hard to tell on the colors because it is neither one. My tap water C02 score is not in the "good" range.

So far, my plants are looking good, but what does this mean for me for the future of my live C02 score?

Should I also test my tank for the GH and KH? I think I did read that both should be tested. ?? I guess I am wondering that if there is a slight difference in KH and pH in the tank that would mean my C02 in the tank can be either greater or less. I assume this would be the case. I am a little confused on this though since there are plants in there that can use up the C02 and fish add to the C02.

Thanks for any help on this so I understand it better.

Angel079 02-16-2010 11:52 AM

Since I posed various links in the past, here's one where you can enter it to have it calculate for you Measuring CO2 levels in a Planted Tank

There's few issues thou:
1) From my exp any & all of my set ups once fully cycled have each their own pH/KH that fluctuates some from the tap water
2) That can be influenced by DW (which then also gives you a inaccurate reading on the CO2 tables)
3) KH can also be upped dep on the substrate used in the tank
4) Also your parameters can differ if you use the water right away from tank/ tap OR let it sit for 24hrs and then test

So in essence what I'm trying to get at is that there's many influencing factors here that possibly could give you a false reading. If you REALLY wanted to test the CO2 like you do with your pH and KH you can get a tester for it (I done the in the past but not any more now).
In most all set up that are properly planted and stocked that will never become a issue if the tank is balanced right with the ferts & lights used. If that balance get's outta wack then you see issues like algae develop. On the other hand when you have a sufficient set up for plants and that works as it is and you add external co2 on top of that again you can create yourself issues that way too.

So if this was my tank; I'd leave things as they are and watch what happens (which I'm sure others then nice growing plants nothing will happen).

Byron 02-16-2010 12:23 PM

First, I stopped bothering about CO2 years ago. In any normal balanced aquarium, there is going to be CO2 produced by the fish and biological actions; decomposing mulm gives off CO2 (which is another reason not to vacuum the substrate in planted tanks;-)). I've no idea what it measures in my aquaria, but I can be very certain of one thing--there is more than enough of it.

CO2 is usually found in tap water. Many suggest when test pH of tap water that you let the water stand (in a glass or jar) for 24 hours. This is to allow the CO2 to escape at the surface, and as we all know, CO2 lowers pH, so if you do this and there is CO2 in the tap water, the pH will be higher after 24 hours. My tap water varies by .1 so there is not that much in the tap water here.

The fact that my plants are obviously thriving means I have a balance between light and nutrients in all my aquaria. As as I have mentioned before in a couple of threads, even in my spare plant tank with no fish, the plants are growing well. So, CO2 must be coming from somewhere and must be adequate.

While typing this, I see Natalie has responded, saying much the same. Don't bother with CO2, it is going to be there. Keep the light minimal and balance the minerals (via fertilizer) and you're set. [I also have a CO2 test kit, years ago, prob not working now, but I could never figure it out anyway; and as the plants continued to grow fine, I decided it was fussing over nothing.] And speaking of flourishing plants, my E. bleheri have sent out numerous flower spikes during the past couple of weeks, I have never seen so many plantlets. I must have more than 20 on 3 plants. Obviously they are happy.


HollyinWA 02-17-2010 10:00 AM

Thanks Angel and Byron. Both of your posts were helpful. I will stick with my plan of seeing how everything goes and thrives. So far, so good. I am loving live plants!

LisaC144 02-17-2010 10:17 AM

You guys are the best! So helpful and sooo knowledgeable. Holly, I'm so happy to hear you're loving your live plants :-D

HollyinWA 02-17-2010 11:04 AM

Thanks, Lisa. :-)

redchigh 02-17-2010 06:02 PM

I just made a post on CO2, PH, and KH-
and as I was typing it, I realised just how complicated it is.
I plan on trying to keep my PH at 7.4 and KH around 12. which gives me a good CO2 of around 12-15 ppm.

Just note that too low, and plants could have trouble, and too high, and the fish will have trouble. Others might disagree, but I'd look at the CO2 chart, find my water parameters, and as long as it's not over 20 ppm co2, you're good.
If you decide to raise your KH to affect the levels, you could read my topic on it.

Byron 02-17-2010 06:47 PM

I don't see this as reliable. I used the calculator on Chuck's website and in my 90g I have 150ppm of CO2 and in the 115g it is zero. Neither of these is at all realistic nor possible. The fish would be dead in the 90g and the plants similarly in the 115g.

In the first place, in a planted tank without CO2 supplementation it is basically impossible to have an excess of CO2 unless you are tremendously over-stocked with fish. And this Chuck person's comment that fish don't produce significant CO2 is very questionable.

On the oxygen side, plants produce far more oxygen than the fish, bacteria and plants can use in return.

Stick to common sense. I have no inclination to start messing around with something that could seriously harm the fish when the basic approach that has worked in planted tanks for more than a hundred years has a proven track record.

Angel079 02-17-2010 07:01 PM

redchigh Its nit as simple as you break it down here, as I said further up there's many factors that make these co2 charts inaccurate. Also co2 levels greatly influence algae so be careful there.

Limitain plants down to ONLY needing the co2 level in the right mix as you say there - I find that dangerous statement; plants need a balance of ALL involving factors being light, nutrition and co2. If you have a great co2 level but no nutrition and no ferts and/or a crappy light plants still will NOT thrive in that great co2 environment then - Its all about the balance people :-)

Angel079 02-17-2010 07:01 PM

Just seen Byron posted at the same time I did - Glad to see I'm not alone with my view's there :-)

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