CO2 must be working, numbers take huge leaps

[fish_4_all]

~Plant(s) affected? Red Melon Sword doing great, micro sword dropping roots all over, java fern growing better than ever.
~Tank size/volume? 10 gallon with AC20 HOB
~Lighting/wpg? between 20-40
~Do you inject CO2? If so do you know the level? Yes on CO2, amount unknown, passive bell diffusion
~What do pH, KH, PO4, NH3 and/or NO3 test kits say? pH - 8.2, KH - 250, PO4 - 2, NH3 - 0, NO3 - 0, GH - 300
~Dosing? What/how much/how often? Only leaf zone twice a week, 1 teaspoon
~Heavily, moderately, or lightly planted? lightly planted
~Fish stock? 4 adult cory, 10 baby cory, 1 small pleco, 1 betta male
~Tank Location (near windows - in direct sunlight)? No direct sunlight, no indirect sunlight, exposed to some room lighting beyond tank fixture.
~How long has tank been set up? 8 months

All numbers checked and triple checked!!!

Readings on 6 march: pH - 7.2, Nitrate - 20, GH - 120, KH - 140, PO4 - 2
ammonia - 0, nitrite - 0

First, how do I calculate my CO2 levels and are they too high?
Second, are the numbers dangerous to my fish? I think the pH is too high.
Third, what do I need to do to get them back to normal if I need to?
One other thing, what could be causing an oily sheen on the top of the water?

 

[rich311k]

Here is a calculator for you.

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

Ph should be going down not up. The oily sheen could be from your food. A papertowel floated on top will help remove it.

 

[fish_4_all]

So I only have about 3 ppm, that makes sense as it is passive injection but why did my KH and GH simply freak out!? Why did my pH go so high?

Am going to do a water change now, will report tommorow on the numbers.

 

[Lonewolfblue]

Your kh degrees is 7.8 degrees. So a ph of 7.0 will bring your CO2 to 23ppm. 7.2 it's only 15ppm. So your goal I believe would be between 6.8 and 7.1 for your ph. Increase CO2 injection til you reach a ph of 6.8-7.1. And since CO2 drops ph substantually, you don't need to up the CO2 too much more. Just bump it up a tad and you will be there.

So basically, if your kh is 140, you want a ph of between 6.8 and 7.1. Your CO2 levels will then be between 19ppm and 37ppm.

 

[Purrbox]

If your using tap water for your tanks and have done a water change between the two tests, check the current stats of your tap water. Often water will have varying stats throughout the year and can change suddenly.

Another possibility is that your testkit may have gone bad. Take a water sample to your LFS and have them test it, preferably with a different brand testkit. This could be particularly likely if you are using dipstrips and they got exposed to moisture.

 

[malkore]

Some facts:

CO2 lowers pH...it can't raise it.
CO2 doesn't affect Gh or Kh in the short term. If you did no water changes and ran CO2 for months and months, you'd dissovle the Kh and it would slowly drop over months.
Normal CO2 levels for water that isn't being injected is 3ppm. so you're really not even getting any to dissolve, or so little, that the plants use it up instantly, and we get no detectable increase in levels.

Purrbox gives some good advice. Test your tap water's Kh, Gh and pH after it has sat out overnight.
Also quite possible the test kits are bad, or you made a mistake in testing (one drop too many, something on the dropper tip caused a larger or smaller than normal droplet, skewing results)

If you are using test strips...stop. Those aren't accurate enough for a planted tank.

 

[PrettyFishies]

What test kit do you reccomend that tests PH in .10 increments?

 

[Angel.Zero]

malkore I have a very lightly planted tank and have an avarage of 16ppm co2 with no injection, is that normal?

 

[sherry]

It probably means something else is pushing your ph down..

driftwood?

 

[Purrbox]

Driftwood won't affect the KH/PH relationship. However it does indeed that there are some buffers in your water that are messing up this relationship and making the standard CO2 calculation invalid. Dskidmore was kind enough to post a link to an article discussing how to calculate CO2 in a tank that can use the standard calculation. Check out her response towards the bottom of this thread.

 

[Angel.Zero]

well the only thinks in my tank are some plants and a piece of driftwood, I don't add any chems so it's not that. could it be my stock is producing that much co2?

 

[Purrbox]

I wasn't talking about buffers added by you, but rather by the water treatment facility. They often do things to the water that can result in some very interesting test results. You're just not going to have that much more than 3ppm CO2 in a tank that doesn't have CO2 injection.

 

[fish_4_all]

6-Mar 8-Mar 10-Mar
0 0 0
0 0 0
7.2 8.2 7.6
20 20 20
120 300 150
140 250 300
2 2 2

CO2 added 6 mar. Red melon sword growing very fast, 2 new shoots in 6 days. Longest leaf has grown at least 1 inch. Micro sword growing very well, lots of roots, new sprouts, some algae growing on it though. Will be doing blackout as soon I am sure numbers have leveled out. WIll have pottasium on the way soon, seems I produce enough nitrate and PO4 without having to add it but will be ordering them too.
CO2 ppm 8-12. Kind of rough but i have to get a reliable test kit for KH and GH. Mine seem to like to have fun with me at my expense and hopefully not my fishes.

What is the highest CO2 concentration I should get, under normal circumstances, with this setup?