Question On Co2, Kh, And Ph.

[vonjankmon]

Ok setting up a high tech 55 gallon planted tank. Got it all set up and started it cycling with some filter foam from my other tank 2 days ago. Curious about a few of the parameters of it I tested for C02 and KH. I have an electronic PH monitor on it so I already knew that.

Here's what I found with my RedSea test kit:

KH: 1 or less, test instantly went to end color
CO2: 6ppm
PH from monitor: 5.2

I'm using ADA Malay substrate which is what I believe has lowered my PH by so much, it was 5.3-5.4 before I began adding CO2, so adding CO2 didn't change my PH much at all. I'm using the RedSea pressurized CO2 system and the little in tank constant capsule CO2 monitor they provide with that has been saying to much CO2 from the second I put it in the tank. All the plants I have in the tank right now appear to be doing fine, a lot of them are pearling and some crypts I bought are looking a bit rough but it's probably just a bit of crypt melt from being replanted. Appears that the ADA substrate is responsible for lowing my hardness and PH so much, beginning to regret spending the extra cash for it.

So my questions become these:

1) What is the best way to truely calculate the current CO2 in the tank? One RedSea test says I have 6ppm, the one that stays in the tank is saying I have over 30 because it's yellow all the time, and by calculating using my KH and PH I have about 189ppm in the tank.

2) What is the most reliable way to raise my KH? And do I need to raise my GH with it? I know you can add Calcium Carbonate to raise both but would it be smarter to buy some crushed shell substrate and just put a bunch of it in my canister filter or should I purchase the stuff ground up to mix with my water and dissolve it in that way? Or would someone recommend a different method?

3) And my last question is how I should go about raising my PH? My fish could probably survive at the current PH but it makes me nervous to have it that low, not to mention while they may survive I don't have a lot of confidence in them thriving at that PH, not to mention riding a thin line there of not having much room for my CO2 injection to drop my PH before it gets deadly to the fish.

Thanks for any and all helps folks.

 

[plantbrain]

What you can do is a series of large water changes and then measure the KH of the tap, and then the tank.
The goal is to do a large % of the tank water=> to tap.

This way, most of the tank water is now the Tap's KH.

Then you measure the pH/KH combo.
This assumes that the KH is entirely bicarbonate, which is not always the case, and that is an issue for the pH/KH/CO2 table.

As the ADA AS removes the KH slowly, you can keep the rate of CO2 steady.
As the pH and KH both fall, the rate of CO2 is the same, so if you have 30ppm of CO2 before, you should have the same CO2, and the ppms should be the same, even if you cannot measure it.

The other method which is fairly simple, is to use a pH drop checker with a reference KH solution, since the KH ref solution never mixes with tank water, and the only gas that changes the pH inside the check is CO2, you can measure CO2 no matter what the parameters are in the tank.

This method does have trade offs, such as a lag time of at least 2 hours, sometimes more.
But it makes a good eye ball estimate for most folks and tweaking the CO2 from that pooint is typically done(slowly), to get a bit more CO2 into the tank without any issues with fish.

There is a 3rd method also.
You can use the water change method, then measure the pH differences at the same CO2 flow rates.

So say the Tap water 90% tank has a pH of 6.2 for the optimal CO2.
And after a week, the pH with this same stable CO2 rate is now 5.6.
You can assume that the drop due to the ADA As is about 0.6pH units. So you use this factor.
This is problematic though. The ability of the ADA AS is lost over time, and tap changes as well etc.
So the drop check and each of these methods as well as eye balling will help.
Do not rely on only one single method.



Regards,
Tom Barr