Those devices are dubious at best and fail to actually remove any calcium from the water.
Since your pool is new and almost complete, you need to get yourself one of the test kits we recommend and you need to read through Pool School to understand how we approach the science of pool water treatment and maintenance.
The way to keep scale from forming in your pool is to properly manage the water chemistry and keep everything balanced. We use a saturation index calculation called the "Calcite Saturation Index" or CSI. If you properly manage your CSI, you will not get scaling. If you allow you water chemistry to drift around and do not properly manage your water, you will get horrible calcium scaling. With a new pool, your testing regimen is going to be daily especially during the critical plaster startup stages. There are no cheap solutions here or quick fixes...it's rigorous self-testing of the water and committed and consistent management of the chemistry levels in your pool.
If you want to plan something for the future, you might consider hooking your autofill line you have for the pool up to a water softener. Limiting evaporation and refill with hard municipal water is the only way to keep your calcium levels in check.