CO2 injection but high pH - The Planted Tank Forum
 
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post #1 of 9 (permalink) Old 04-05-2010, 04:04 PM Thread Starter
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CO2 injection but high pH

So here is my problem.

I have tried a lot of things but Im confused as to why this is happening.

My 55 gal tank is moderately planted with two 54w t5 ho lights.
Parameters:
ammonia: 0
nitrites: 0
nitrates: 20-40
dkH: 1-2
dGH: 9-11
pH: 7.6
Phosphates: 1.75 ppm

Based on the equation from another website my co2 is low, 2-5ppm on average.

I have two DIY co2 reactors being fed into my submersible filter through the air intake. I use this filter as an additional heater, water mover, filter, and (originally) oxygenator. Now the air intake is strictly co2. I also dose daily with seachem excel.

I used to add aquarium (conditioning) salt when I did water changes. (Which I know raises pH) But I have only done that once or twice since I started the tank with plants. But Consistently my pH has been raising about 0.1 every week or so. My tap water is about 6.6-6.7.

I guess my questions are:
a) what can I do to keep my co2 levels up without a canister?
b) Should I be using this equation CO2 (in PPM) = 3 * KH * 10( 7-pH )
c) How do I get my hardness up and my pH down?
d) can I do this without adding too many chemicals (i believe in keeping it as natural as possible)?
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post #2 of 9 (permalink) Old 04-05-2010, 04:31 PM
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your GH is high i would like to keep minds about 6- 8 at the highest. hmm mayb add a nice piece of drift wood to soften the water that will also bring down ur ph. Make sure u dont have any rock ur tank that raises ur PH like tufa, lace or coral. Do a 50% water change. and work from there
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post #3 of 9 (permalink) Old 04-05-2010, 05:44 PM Thread Starter
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Quote:
Originally Posted by bkrivera View Post
your GH is high i would like to keep minds about 6- 8 at the highest. hmm mayb add a nice piece of drift wood to soften the water that will also bring down ur ph. Make sure u dont have any rock ur tank that raises ur PH like tufa, lace or coral. Do a 50% water change. and work from there
Thank you for the response.
My substrate is a mix of (85% flourite, 8% large aquarium stones, 5% small aquarium gravel, 1-2% play sand sand)

I added two pieces of driftwood about 2-3 weeks ago. They aren't any special malaysian wood or anything, just regular old bogwood from a local creek that I boiled the crap out of. Our tap water has a high gH to start with (i think right about your range) Ill have to refer to my charts when I get home for an exact measurement.

My other tanks are keeping their levels in check so Im curious if there are any other contributing factors that might cause this since, I do a weekly 25% water change. Do any other fertilizers cause pH swings such as Leaf Zone pro?... well, that might not be it either since I used that in my other tanks as well.
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post #4 of 9 (permalink) Old 04-05-2010, 07:27 PM
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If those lights are sitting right on top of the tank you have high light intensity, high enough that you need to use pressurized CO2 to keep the CO2 concentration in the water high enough and consistent enough to meet the growing plants' needs. DIY CO2 will not work.

CO2 (in PPM) = 3 * KH * 10( 7-pH ) works only for water that has nothing in it to affect the pH except carbonates (bicarbonates) and CO2. Tap water very rarely meets that criteria, and aquarium tank water even less so.

With the amount of light you have you also need to dose a complete menu of nutrients, N, P, K and trace elements. None of those, dosed correctly, affect the pH. Aquarium salt should never be used for a planted tank.

Tap water may contain lots of CO2, which lowers its pH. But, once in the aquarium, the CO2 dissipates and that causes the pH to rise. The CO2 fluctuation that this causes is also a trigger for algae to start growing.

Hoppy
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post #5 of 9 (permalink) Old 04-05-2010, 08:12 PM Thread Starter
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Hoppy, Thank you so much for the information. I am really appreciative of all the answers I am getting from the users here. Your knowledge is invaluable.

I figured that the 108Watts was still an insignificant light source to need pressurized co2, but I will take the advice of a professional. I guess its time for me to go investigate some options. To your point as well, My other tanks that have lower pH's are less heavily planted.

And I do have an algae bloom that has been a slight problem until I started dosing with excel. Now its under control.

Should I buy a co2 test kit to more accurately measure the co2 concentration in the water? And do you have any suggestions on the best type of test kit for this?
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post #6 of 9 (permalink) Old 04-05-2010, 09:26 PM
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Quote:
Originally Posted by Joefish4jc View Post
Hoppy, Thank you so much for the information. I am really appreciative of all the answers I am getting from the users here. Your knowledge is invaluable.

I figured that the 108Watts was still an insignificant light source to need pressurized co2, but I will take the advice of a professional. I guess its time for me to go investigate some options. To your point as well, My other tanks that have lower pH's are less heavily planted.

And I do have an algae bloom that has been a slight problem until I started dosing with excel. Now its under control.

Should I buy a co2 test kit to more accurately measure the co2 concentration in the water? And do you have any suggestions on the best type of test kit for this?

Hoppy's advice is right on...

I run 2x54 T5HO over my 50 gallon tank (19" tall) and have the fixture hung so it is 32" above the substrate, even with pressurized CO2 I can get algae if I am not careful. Excel can be very helpful with certain types of algae. Also good to add it as a back up carbon source until you tweak your CO2 to the proper level.

The CO2 test kits are a waste of money. A CO2 meter is very expensive and not really an option. A drop checker with 4 dKH water and some bromothymol blue (standard pH reagent) can be used to monitor CO2. The water in the drop checker will turn green when you have approximately 30 ppm of CO2 which is a good level to shoot for. From there you can tweak it up slightly if you need to. With CO2 never increase the level unless you are going to be home to watch the tank.

You are not going to be able to get adequate CO2 levels in a 55 using DIY CO2 and high light.
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post #7 of 9 (permalink) Old 04-16-2010, 08:46 PM Thread Starter
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All,

Thank you so much. I went and dropped some moneys on a 5 lb can and a regulator. Within one day my pH was back to stable.

Three days my grass got greener.

One week my algea started disappearing, except for the blackish algea that covers the leaves. The Hair algea is no more though.

I appreciate the help on this, everybody.
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post #8 of 9 (permalink) Old 04-16-2010, 08:51 PM Thread Starter
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I also just moved all of the DIY stuff to my 10 gallon and my wisteria and HC are flourishing! (with daily doses of excel too). I'll add pics to my tank profile when I get a chance... Its amazing the difference you see in just a short amount of time.
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post #9 of 9 (permalink) Old 04-17-2010, 09:12 PM
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Quote:
Originally Posted by Joefish4jc View Post
I also just moved all of the DIY stuff to my 10 gallon and my wisteria and HC are flourishing! (with daily doses of excel too). I'll add pics to my tank profile when I get a chance... Its amazing the difference you see in just a short amount of time.
Glad to hear this all worked out for you. DIY is much more "doable" on a 10 gallon. As you have already noticed pressurized is more appropriate for a 55.

Good luck with the tanks!
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