Originally Posted by MoneyMitch
good theroy with the kh you have there, any plans with co2 issue?
CO2 issue? There's no issue there. Seeing as the CO2 acts primarily as a source of carbon, the plants get this from the KH component. When the lab tested my water CaCO3 was the primary constituent and I am certain that this is an alternate source of carbon. The slowing down may also be from the other constituents of the KH not being utilized by the plants so there is likely to be some baseline that it will not go below. Seeing as I start from a 20dKH, my baseline might be higher than someone with a 10.
I saw this play out in my main tank as the KH lowered by over 25% while there were very few fish. As I increased the fish load, thereby increasing the CO2 production, the plants continued to do well, at least as well, but the KH has not continued to fall... at least not nearly so dramatically as it stabilizes at a higher value with more fish present. I don't think that the plants are doing any better with higher CO2 than with higher KH.
I'm thinking about trying some solutions of hyper hardened water to add to the jug. Either evaporating my already hard water to increase the concentration while keeping the same contents which might serve to increase the GH more than the KH over time (TDS issue arises here) or just crush up some egg shells to provide a purer source of CaCO3... either that or play with some antacid remedies, I expect they would have other crap in them though. Eggshells would be easier and quicker than a limestone method, which could be an option.
I still wonder about the reasoning behind the CO2 injection. I am trying to stay ahead of plants that are threatening to grow out of my Aquarium (not this little jug). If I upped the light, nutrients and added CO2 I would just need to garden far more often and my expenses and time expenditure would be greater. I know there are many plants that do better with higher CO2 as their carbon source, and obviously plant only tanks would be high in the list of those that could benefit from it, but if the only reason is to provide more carbon in a useable form for the plants in the water itself, wouldn't a soluble substance that can be just added to the water occasionally be easier than having to monitor bubbles and adjusting regulators?
Having said that, I don't agree with the liquid additives with their inherent preservatives.