Thanks Tom. I have always used a kh of 3 or 4 with pretty good results an stable ph. My r/o is very good. My TDS on a good day is 16 since my tap has very high TDS usually around 530. So I am using a membrane thats is supposed to be 99% rejection but since the water is very warm out of the tap its not realistic to expect 99%. That being said 16 is good for what I am working with.
Just change the membrane and prefilter and the Carbon prefilter(the most). Back flush every month or two also.
Keep an eye on the TDS, it's easy to check.
There's no need to add that much to the KH, only if you blend, then 3-4 KH is a good target.
If you use 100% RO, then target 1 KH with the baking soda etc.
No need to add 3-4 degrees worth.
I am still confused on how the CO2 is still present in the same concentration because at 6.3 or close to it with the kh of 1 I should have about 15ppms of CO2 going by the chart. Now when I raised the kh to 4 degrees I should only have about 6 ppms of CO2 as my ph reads 7.3-7.4.
There's no errors in the chart(my assumption), there are errors in your measurement and assumptions of the measurements.
If the tank water is truly fully degassed, then the CO2 would be the in the 2-3 ppm range or thereabouts. My tanks had 20 ppm after 14 hours of no CO2 added even with high flow rates. I switched to sump/wet/dry filters, now the water degases to 2-3 ppm after 45-60 minutes after the CO2 is stopped.
Canister filters stink for degassing CO2 and adding O2.
This was true on 6 different tanks. Not just one.
O2 levels shot up also.
You know something is not right, but you doubt what it is..........
So let me pose a question to you: do you think the chart is wrong, or something that you did is wrong?
Which would be a better assumption? I'll let you answer that on your own.
Now I am only using regency ph test kit. I only had a digital for a loan for awhile . I found the digital to not hold that well. The regency seemed more consistent. I am sure there are better units out there but I do not want to get into that. I use to work in a lab an I used expensive ph meters to measure deionized water. I just want to know why the co2 content changes when adding kh according to the chart?
See above. Your answer in the paragraph right here.
Standard American Marine type pH meters run about 90$ and replace the probes about once a year. These tend to be very consistent.
Stray electrical current, non shielded ballast and other sources will reduce the pH on pH probes, so turn everything off and THEN, take your reading. If it's drops when you turn things back on, then your know there's stray current impacting the pH reading.
As you can see, and as I've told folks 10,000 x in the past, CO2 is not a simple thing.
"My plants have algae or they are stunted or they do not grow for X, Y and Z but my CO2 has to be correct"
If I had a nickel.............
Then they add more and still do not get the results they want, or gas their fish etc.
But measuring it and adding enough O2, degassing rates, good circulation etc all play a large role there also.
Most only hear, "add more gas".
I'm saying this for the benefit of others that might read this as well as you.
Some of these things might seem obvious to you, but no to others.
Still, I get dogged by simple stuff all the time with CO2. So I try and be careful if I see anything not quite right and always question myself and my own mistakes/assumptions rather than the chart.
You say the CO2 stays the same. But if you compare the levels of co2 to the new kh level they are not the same.
Well, did you add more CO2 or take any out?
If not, then it's somewhat safe to assume.............they should be identical.
How you measured it? Perhaps not a safe assumption.
What is the difference in taking a ph reading in a planted pressurized tank an going by the kh chart to figure out what your CO2 content is? I know CO2 is an acid so adding kh would reduce this acid being the co2.
You did not understand the last post.
CO2 gas forms CO2[aq] in water. Only as tiny fraction of said gas will combine with the carbonate to form carbonic acid. 1 out 400 molecules of CO2 will form the acid with the KH.
You seem to assume it all does this. If that was the case, you'd have no KH left. Think about it. Measure your KH with and without CO2 gas addition. It'll be the same. Adding CO2 gas enrichment to an aquarium is very different than natural systems. We want CO2 [aq], we do not care about pH directly or KH really.
I guess its the aqueous part I am not getting? After a day or so would it be more accurate? But then you will lose a lot of gas?
Yes, the [aq] part messes up folks often, this is one of the harder things for hobbyists to understand, so do not feel bad. You want the water to equilibrate with the air, that acts as a reference point.
Now if you add say enough CO2 gas to knock the pH down 1.0 units from THAT fully degassed reference point, now you likely have pretty close to 30 ppm added extra.
You can check this with thr chart at 2-3 ppm and then look down 1.0 pH units and see now you have about 30 ppm in most KH's. The KH levels/degrees do not matter. A KH of say 10 degrees has a pH/KH of
10KH: pH 8.0 = 3 ppm CO2
10KH: pH 7.0 = 30 ppm
pH of 6.8 = 47.5 ppm of CO2 etc.
A KH of 1: pH 7 = 3.0 ppm
KH of 1; pH of 6.0 = 30 ppm.
In BOTH cases we add the same volume of CO2 to drop the pH because we adding mostly 99.75% CO2[aq].
We are adding CO2 for the plants, not to monkey with KH, acid base equilibra, some Baloney about pH stability etc. Plenty of Hee haw on the web on this topic. Believe me.
You say wait 24 hours to stabilize . Finally thats the answer I have been looking for this as well. There is hardly any info on stabilizing r/o water on the internet. Very little on how to add natural trace back in as well. Thats another subject.
Finally, What would the best time to do water changes using this method to avoid a BBA bloom because of CO2 flux?????? Would using freshly made r/o be better since it has more CO2 in it going into a pressurized set up before or after lights on? Or would you want to age the water an degas it an change at night only or in the morning before lights on????? Either way, there will be some CO2 flux. If enough ambient light is present you would figure a bloom is eminent? BBA seems sensitive to even slight CO2 changes.
Well, 24 hours is okay, some use 48 hours, I use a shallow thin pan to do it. This makes degassing rates faster as shown by Fick's 1st law of diffusion.
More surface area and then less depth of the layer requiring to be degassed. Think about it like this, what cools off faster after taking out of an oven: a thin cookie or a thick brownie? Clearly, the cookie.
Same type of thing here.
If you use CO2 gas,m the more times you do water changes, the better as a rule, the time of day is not that important really. I do mine before or right after the lights come on personally.
BBA blooms seem related to CO2 issues and folks not adding enough, but adding some. And there's often a delay.............maybe 1-2 weeks, then it becomes a real PITA to keep up with it, but if you correct the CO2, then the bloom and NEW growth stops. Now you trim off the infested plants and the new growth will remain clean.
For BBA on non live materials, peroxide or scrubbing or removing and dip in hot water, Excel etc, if you can spray larger non live materials with Excel, without hitting the live plants, when you do a large water change, that will work well also.
Once you master CO2 well, BBA is a non issue really, you might screw something up and then need to beat it back, but it's just par for the course and you know why and you fix the CO2 issue and try to avoid them in the future.
Example, sometimes my CO2 gas tanks run out and I do not catch it for a few days. Hard to view the gauges under the stand etc. I can see the plants are not growing so well as before. So I check the CO2. Ferts and light can be added consistently pretty easily.
Happens to everyone. Anyone that say otherwise just needs to be patient and it'll happen to them.