Lots of great replies here - thanks!
Let me ask a question: why raise kH? What kind of fish are you trying to keep? If your fish don't need alkaline water, I think it's probably better not to raise kH at all. Many people on this forum, in fact, use straight RO water. If you are doing a planted tank, though, just make sure to dose traces. If you want to raise gH, try some of Rex Grigg's gH booster. The pH drop from pressurized CO2 only looks alarming, but is generally not harmful to your fish.
I don't have any fish that need more alkaline water - in fact, most of the fish that I've chosen either like it somewhat soft or don't really care (apistos, corydoras, gouramis). I was planning on raising it just to keep the tank's pH up after I added CO2, but if doing so isn't that important then I won't.
Definitely add CO2 if you are going to upgrade your lights. The pH controller is kind of nice, I suppose, but I think using just a solenoid works just as well. I would definitely get a drop checker if you are going to add CO2, particularly if you are going to adjust gH. Read through Rex's CO2 guide for all the parts you need, that way you can save on shipping. Any plans for diffusing the CO2 yet?
OK, good to know - I might look into just hooking up a solenoid to my light timer or something and try to resist the gadgety approach.
I hadn't thought about how I was going to diffuse the CO2, actually. Any suggestions? I've come across some prebuilt diffusers and reactors, as well as a bunch of plans for DIY reactors, but I haven't really made any decision one way or the other. I might just go for some sort of off-the-shelf bit for simplicity's sake.
I would just avoid dosing macros and trace on the same day. I think it was potassium that combines with iron in the trace and makes it precipitate out of solution. Not a huge deal, but makes the iron inaccessible to plants and makes the water a little ugly. There was a thread earlier today on it.
Sounds like a good plan, post a journal when you're ready. Welcome to the forum!
Ah, didn't know that about the macro/trace combining like that - also good to know.
I'll definitely post up some pics or a journal or something, but I might wait until the tank is looking a little less embarrassing.
I wouldnt be too fussed about raising the KH.
My tapwater (and tankwater) is between 0 and 1 dKH. My CO2 is on a timer so its only on during the daylight hours. pH is around 6.0 at its lowest.
I used to add baking soda for a while only because I kept reading on the internet about "needing" KH around 3-4... but this is old information. Provided your KH is not absolute zero out of the tap then you'll be fine. I stopped adding the Baking soda and let the waterchanges return the tank to an equilibrium matching the tap water - if anything plant growth has improved.
OK, I must have read the same information as you then - I'd read lots of stuff that kept repeating how vital it was to have a KH > 3 when you're using CO2. As I mentioned above, that was my only real motivation for raising the KH at all.
My tapwater's KH is not at zero, but it is pretty close - it's around 3ppm carbonate hardness according to my local water authority. Total dissolved solids are something like 17ppm. If my dodgy cheapo KH test kit is to be trusted, my tankwater is somewhere in the region of 0.75 dKH.
My tap water is also very soft, 0-1 dKH/GH, TDS is 45. I do add a little bit of buffer and mineralize just a little at every water change. I don't target any sort of range, I do though add 1tsp each Equilibrium and baking soda for my 75 gallon tank. If you do the math you'll see it's not much at all, because to go any further would create more of a gap between the fresh new water and old water in the tank than I would like. Anyway, just a slightly alternate viewpoint to those already expressed, but otherwise I agree, the less one fiddles with the water, the better.
Yeah, I generally try to fiddle with my water as little as possible too - the prospect of doing so was what was concerning me a bit. I might do something similar to what you're doing - toss in a small amount to bring it up from near zero, but otherwise leave it be to avoid any big tapwater/tankwater difference.