On Mon, 28 Jan 2002, David Sanchez wrote: > My point is that there is a correlation between KH, > pH,and CO2. This what I said > > David said > "hy are yoiu using a CO2 system if you have water > > with > > > oKH to begin with Colin? The lower the KH the > > higer > > > the CO2 level." > > > My > point is that if you have a low KH and low pH there is > no need for CO2 injection because using these factors > we are able to determine the level of CO2 in a system > of water. The fact is that by measuring the level of > both pH and KH you will have the CO2 level in your > system. From this premise we can determine why we do > or do not need a CO2 system in our aquaruims. And my point was that this statement is UNTRUE. CO2 level is entirely determined by external factors, such as atmospheric concentration, injection, and respiration. So to claim that Colin's tank has enough CO2 because his KH is very low is untrue. Now, if you are using the "charts" to determine the CO2 concentration based on the pH and KH readings, you should understand that whole triangular relationship between pH, KH and CO2 breaks down at low KH, because it is no longer a buffer solution. The pH can fluctuate wildly with even the slightest change in CO2 level (or frankly, with any other acid or base added to the system). There are some nice analyses by Roger Miller and others on the APD on that same URL I gave you for the chart that shows how little you can rely on the charts, especially at the extremes. > I have not had a CO2 systemn in any of my aquaruims yet my tanks have > lush plant growth. I do need a CO2 system because I already have > enough CO2 in my system. DO natural bodies of water have CO2 > injection? no they do not. My point here and what awe are discussing > is the need or lack there of of a CO2 injection system. Just saying > you have to have a CO2 system to have good plant growth is not > corrrect and is based on a lack of understanding the relationship of > all the given data. "Good" or "Lush" Plant growth is a very touchy and subjective subject amongst plant enthusiasts. In our fishroom, Kathy and I have some 25 tanks. Most of them have a single tube of fluorescent light over them (maybe 1.5 watts per gallon), use aeration, and grow plants like Anubias nana, Water sprite, and Java Fern quite nicely. In three of our tanks, we have double that light, use power filters, and bubble CO2 into the filters. These tanks grow more "difficult" plants like tenellus and Sag. One tank has maybe 4 watts per gallon and injects CO2 through a reactor, and I fertilize with Tropica Mastergrow. In this tank, we grow our most "complex" plants like Rotala macrandara and Glossostigma elatinoides. All these tanks could qualify as "lush", but by different standards. Anyway, this is using up more time than I have. For more info, I suggest reading the Krib or archives of the Aquatic Plants Digest. - Erik -- Erik Olson erik at thekrib dot com ------------------------------------------------------------------------- This is the apistogramma mailing list, firstname.lastname@example.org. For instructions on how to subscribe or unsubscribe or get help, email email@example.com.