water chemistry and dissolved co2

vequalsir

vequalsir

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Jul 7, 2008
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Cleveland, OH
www.sayresaves.com
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Tom Trautman
I'm looking at adding a DIY co2 set-up to my tank. Before I hook it up I want to be sure that I'm understanding my water chemistry first. I don't want to harm my fish trying to grow plants faster.

I have API test kits for ph and gh/kh. I did a partial water change yesterday and tested water parameters this morning.

My ph is 7.3
kh is 5 degrees
Gh is 179ppm
light is 1.4wpg

According to those numbers my co2 is at 7.52ppm.
(co2=3*kh*10^(7-ph)

I'm currently not injecting any co2 into the tank; however this number seems high. I read that I should see 3-4ppm normally.

What else do I need to check for? Phosphates? I don't add them, but perhaps they are in my water.

Any help would be appreciated.

Thanks!
 
What you're experiencing is the breakdown of the pH vs KH chart. Other components in your tank can affect your water chemistry, including rocks, driftwood, even components in your tap water.

Wtih a KH of 5 and a starting pH of 7.3, you are safe to add DIY CO2. If you are lucky, you'll see a pH drop down to around 6.3-6.4. That's hard to do with DIY CO2, even harder to get more co2 than that. It's nearly impossible to inject harmful levels of co2 with the DIY route. Only if, and when, you go pressurized should you worry about this.
 
With DIY CO2 you cant really harm your fish.. unless you add 10 bottles and have 100% diffusion then thats a different story..
The ph/kh chart is inaccurate btw

The only thing you would have to worry about when setting up diy co2 is not the fish but how well it will be diffused in your tank (aka your method of diffusion) another thing is what filter you will have on the tank (HOB vs Canister)

What plants do you have in the tank??

If you do go with co2 you might also consider adding trace ferts once a week or so.

Edit: Ninja'd by Jeff
 
I do have driftwood in my tank. I'm also using a HOB filter.

Is there a better way to track the co2 content of my water? I know I could get a drop checker; however these appear to work on the relation of ph and kh as well.
 
Fordtrannyman said:
Possibly!
You can obtain a water quality report from your local water district.
Click to expand...

That's good info. I think I'll do that myself. Been wondering about my local tap water and thinking about using bottled. This will tell me f it's worth the hassle. Thanks.
 
Drop checker's do rely on the GH vs KH relationship, but you eliminate outside sources of error by using RO water reconstituted to 4 dKH inside the drop checker. That way, you know for sure that the only thing affecting the pH inside the drop checker is the co2, so pH vs KH works inside the drop checker.
 
jmhart said:
Drop checker's do rely on the GH vs KH relationship, but you eliminate outside sources of error by using RO water reconstituted to 4 dKH inside the drop checker. That way, you know for sure that the only thing affecting the pH inside the drop checker is the co2, so pH vs KH works inside the drop checker.
Click to expand...

good point...thanks
 
Mindcrime121 said:
Been wondering about my local tap water and thinking about using bottled. This will tell me f it's worth the hassle. Thanks.
Click to expand...

I apologize for being off topic. In some areas, bottled water is local tap water (filtered). The coke and pepsi brands just filter tap water at their plants. Another consideration is that tap water from many municipal systems is subjected to more stringent testing (for safety) then many bottled waters.

On topic, a drop checker never hurts, if only to target CO2 levels. As far as the inaccuracy of CO2/kH/pH tables or calculations, these are simplified. Gas levels in solution are also dependent on temperature. Another consideration is that you are most likely only using hobbyist kits, even the good ones have a margin of error that is notable.
 
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