I really don't think you are in much danger switching salts if you keep the initial water changes small, but I'd still dose kalkwasser instead.
The rise in calcium happens within 24 hours. What I do is take a gallon jug of distilled water and mix the kalkwasser in it. Shake it up really well and let it sit undisturbed for 24 hours. This mix is good for about a week if you want to store it.
Here is how I dose it. Since I have a 55 gallon with mh lights, about a gallon of water evaporates per day. I just add the kalkwasser as topoff. I place a piece of plywood on my tank and then set the jug on there with the cap off (a little bit of the jug hanging over the edge of the plywood). Then I poke a hole in the jug where its hanging over (with a saftey pin) and let it slowly leak out.
It takes about an hour or two to empty, but slow is good when dosing.
If I recall you have a slightly smaller tank...like 29 or 37 gallon, right? You probably can't dose the entire gallon jug all at once so you need to either only mix the amount you need, or stick around to watch it. If you want, you can go to the local hospital supply store and get an I.V. I used to hang the gallon jug on a coatrack andlet the I.V. dangle over the tank lol.
I also bought a doser (which I returned). Since our tanks are on the smaller side, I think simple is better.
ps- take care not to shake the jug after letting it sit for 24 hours. The white powder on the bottom needs to stay OUT of the tank. Its ok if some gets in, but try your best not to.
