Join Date: Apr 2009
Location: Amherst, NS Canada
I've never used RO water so my opinion on it may be of little value. I've been able to manage tanks without it successfully, therefore, I believe that it probably isn't necessary in the majority of cases. In theory it would be of benefit if your water contained something like salt that would be detrimental to plant growth. Others will undoubtedly disagree.
I do have a couple of thoughts on your predicament.
1. Hang in for a couple of more months. Some planted tanks will take a year to "settle in". Not sure why but I believe the biological processes involved with the planted tank have not matured adequately to provide the stability that benefits plants and gives them the advantage over algae.
2. Make sure your plants are growing at the maximum speed possible given the light available. Personally, I wouldn't have more then a 9 hour photoperiod. You've been given advice on CO2, so I won't mention it again. I'd suggest water column ferts, I'm not sure from your other posts whether you ever tried them. I am a fan of EI, at least as a starting point. With EI you can pretty well rule out ferts as a limiting factor. I realize you put in MTS to avoid this but it doesn't seem to be working. If you are concerned with the algae benefiting consider the fact that the algae has done quite alright without them, so what can it hurt?
3. Be relentless in tank maintenance. At least once a week, probably twice would be better remove all visible algae. Remove plant leaves that have been overcome by algae. Do a 50% water change once a week.
4. Make sure you have the tank well planted with fast growers (that are growing fast). I do believe that plants and algae compete for dominance in their environment, this tips the balance in favor of the plants. Floating plants are not a bad thing either. They grow fast, take some of the edge of your lighting and seem to benefit my tanks.
Maybe you've tried all of this, its hard to tell from your posts what you have or haven't tried. And keep in mind, this advice will not make all your problems disappear next week. I think you should see results within 4 weeks. Plants will grow faster, algae will grow slower. As the tank stabilizes you should be able to cut back on a lot of this, remove the plants you don't want, cut back on ferts and water changes if you like. And see what happens from there. Good luck with whatever you try.
Wishing I had a pithy quote