finally got scrubber up and running

Sorry I just saw this! Was sick for about 2 weeks (pretty much) and then spent the weekend on a forum upgrade (for our club)

I don't but I really need to. After listening to Bob Fenner speak at our last fest, it comes down to this: If you never want to add anything to your tank again, then you might be able to get away with no water changes, because everything in the tank becomes accustomed to the "soup" that it is in.

Generally, this is not the case for many people though. Chemical interactions are the thing that causes corals to fight and die, and it probably affects fish too. So it's a good idea to do water changes not related to nutrient reduction. That takes a big chunk out of it. So you're down to 10%, probably every other week. 20% a month is probably a minimum. Most advice is double that (20% every other week or 10% a week).

 

Looking great!!

As far as adjusting things, first a few questions: how is the tank? N & P in check? Tank algae anywhere?

 

I'm not sure what you could do about that either. I can tell you that if you repeatedly change your flow patterns, this does disturb the bacteria in the system and can cause mini-cycles. It's best to get your flow patterns established as best as possible, and then leave them there.

Diatoms is what you are seeing, and they are one of the oldest forms of life so they are pretty adaptable. It might wane over time, hard to say.

I would say that you have a pretty well balanced system right now if you have N < 1.0 and P =0 (but what P test are you using?)

If you want, you can bump the photoperiod up to 10 or maybe 11 hours/day, make small changes. If you have low nutrients already and no major tank problems, you don't want to overdrive the scrubber.

 

^ corrected this to 0.06ppm or 18ppb on ULR before conversion (just a note)

Remind me, do you have any other phosphate reducers online in the system?

 

What I have found in the past is that the dark slime coating was a result of too much light, or light for too long. But now I'm not totally sure of that, it might just be a growth phase that is related to the tank adjusting it's "set point" to a new one after adding the scrubber. The reason I think this is because I started out getting growth like you have on my scrubber on my tank (when I switched it from the L2 UAS test unit to the L2 waterfall) and I would get that slime coating if I ran the lights too long. But I don't get that at all anymore. Recently I accidentally left the timer in the "outlet on" position so it ran 24/7 for a week, and I got a ton of growth in 5-6 days, easily equal to what I got in 10 days or so running 12 on/12 off. So I left it there, and after cleaning it once I've got the same result - thick green, no slime. But I'm also feeding daily 2-3 cubes instead of every other day, so that might have something to do with it.

Since you don't have a lot of N or P historically, I wouldn't drive it too hard or you might end up starting to get some recession in growth. As long as you are getting the net results you want, don't worry too much about the type of growth you are getting.

It doesn't hurt to swipe off the slime with the palm of your hand like you are doing, so you can keep doing that. You might try just letting it grow without touching it at all for 4 or 5 days, the slime coating might not get any worse.

 

How are the water parameters and tank algae?