Re: 60l tank setup
Thanks for your questions and your nice words about our products, and we wish you much success with your new marine setup! I'll try and answer your questions as they were posed:
1. Though the choice of whether to start with natural sea water or artificial is ultimately up to you, my personal opinion is that consistency is the best idea. For example, if you were going to continually use the natural water for your water changes, etc, then I think it would be fine to start out with it; however, since you ultimately will slowly switch over to using a synthetic sea salt, then I might suggest just starting the tank out with RO water and Marine Salt. Again, this is purely opinion, and it is your tank, but to be the most consistent with parameters, etc, I would probably start out with what you plan on doing long-term.
2. When the need for top-off water arises due to evaporation, RO water alone or RO water with Marine Trace will be fine.
3. As a general rule, a 15-20% water change weekly or biweekly will allow for optimal overall water quality. For a 60L tank, a 10-12L change will be sufficient.
4. Yes, you can use Purigen in place of a protein skimmer, and it should do a fantastic job of clearing your water and removing nitrogenous organic waste. Some call it a "protein skimmer in a bag"!
5. Wow, sounds like you have pretty much everything covered. One thing I would suggest since you already have the Stability on-hand is to add a little Stability to the tank with each water change (after the cycle has completed) to replace any potentially lost colonies of beneficial bacteria during the water change process.
We hope this information has been helpful, and let us know if you have further questions. Have a great weekend!