Water Params

[denzil]

... Are there any alternatives to water changes? ...

The simple answer is yes.
You need to add the missing nutrients and minerals. Testing + Dosing. (Not just dosing)
You need to remove the pollutants. Various biological and/or chemical ways to do that.

Complicated. Bad things happen if you make a mistake. But possible.
Recommended when first starting : NO.
Easier/Harder : Always a fun debate.

I'm open to a challenge. It'll just force me to understand the chemistry behind it which isn't necessarily a bad thing. Yay for learning!

Well, pick a method, give it a whirl.
Everyone gets something different out of this hobby. I like the engineering and chemistry as much as the fish.
Heck : You started this thread.
http://www.bareefers.org/home/node/14967

Yep and I still plan on following through with it. I just need to get my 40B set up first.

Hmm. That might be a bit small for playing around with no water changes.
Step 1 : Mega Sump.

A sump was definitely not outside of the scope of the hypothesis.

 

[lattehiatus]

Check on phosphates if you aren't running gfo or similar yet. It can inhibit the corals use of calcium, so even if it is high enough on a test the coral could have effects similar to low ca.

+1 on checking PO4, particularly if you are feeding moderately to heavily.

Relying on water change to maintain parameters becomes increasingly challenging as your stocking of corals and fish increases, and is not fun with anything but nano tanks. Kalkwasser is great at replenishing alkalinity but not so effective at replenishing calcium. It has the added advantage of precipitating phosphorus and heavy metals. Otherwise, consider doing sodium carbonate or sodium bicarbonate. The magnesium at 1420ppm is not out of the stratosphere and will be naturally depleted over time.

I thought Kalkwasser was great for replenishing calcium and alkalinity while providing a great pH buffer? I guess I'm still a little unclear about how Kalkwasser works. So I guess doing a two-part would make more sense or do I have it backwards?

Well kalkwasser is calcium hydroxide, which reacts with carbon dioxide to form two parts bicarbonate to one part calcium ion. That means it is balanced, since calcium uptake by calcifying organisms is typically accompanied by the uptake of two bicarbonate molecules. The 2:1 ratio of bicarbonates to calcium means that if you are trying to increase your calcium levels, and assuming your tank's uptake is less than what you are adding, you will need a lot of kalkwasser to actually increase the calcium level of your tank water compared to alkalinity.

Running out of free internet time at the airport so I'll come back to this later if it doesn't make sense.