Nualgi

I've used it on my 75 gal. I don't know what I think about it. I discussed it with Randy Holmes-Farley on a forum and he had me look at his discussions about dosing sodium silicate, which is pretty much all Nualgi is. It definitely stopped my film algae and early on when I used it, it made my hair algae die off. It does nothing to stop stuff like bryopsis or bubble algae though that I've seen. I can't really say whether it's directly benefited my corals, it's had a cosmetic benefit. The downsides are that you have to dose cautiously initially because it can cause a diatom explosion. I think it also has some effect on causing bonded nutrients to be released from the sandbed, other's have claimed this as well but it is anecdotal evidence at best. I got a carpet of green algae that formed on my sandbed after dosing it for a few weeks, which was then slowly eaten or died off and hasn't happened since. One other downside is that apparently it has Molybdenum in it as some kind of byproduct or buffer and it can raise your levels of that too high if you don't do water changes very frequently. So, the best I can tell you is that it definitely got rid of film algae and hair algae. I've stopped dosing it however because I want my algae scrubber to have maximum growth and I found that adding Nualgi slowed it down.

 

I used this stuff for about a year. My tank had hair algae that would grow on my return lines and power head cages, the rest of the tank was clean. This was my experience.
When I first started adding it I had a "small" diatom bloom which lasted 2 weeks. Within a month there was no algae on the return lines or power head cages. I only had to use my magnet cleaner on the glass about once every other week.

I also run an algae scrubber as the sole filtration. I was concerned that this would weaken the scrubbers effectiveness. What I noticed was the scrubber produced a Brighter green algae, not significantly different in volume from what it had produced before using nualgi.

I used it for about a year, then I ran out and never repurchased it, that was about 8 months ago. The algae has returned to my loc lines.

I can't speak to the elements in your tank it may throw out of whack. I always dosed it at about 3/4 the recommended amount.

I would say it works as described. Regarding the diatoms, the company states up front that this will happen you need to dose very conservatively for the first few weeks. I started at 25% of the recommended, and still had a small diatom outbreak. Nothing like when you set up a new tank, but noticeable.

 

Here's the article he linked me to. Feature Article: Silica In Reef Aquariums