REEF2REEF Saltwater and Reef Aquarium Forum
A ziplock baggie will work in a pinch. (Runs some searches or click this tag #lux to see some threads where folks have done this in the past.)
That said, I do all measurements at the surface.
The relationship with the measurements underneath are coincidental and mostly predictable to within the degree that corals care. We need to hit a range, not a specific number.
Mostly that means >10,000 lux. But technically corals can go even lower under good conditions.
But that's not all...
You might want to remove 90% of your chaeto or even try running the system without it for a few weeks....I bet your corals perk up.
And maybe I didn't mention this detail on the post I linked (but hope I did!), but your phone in a ziplock bag IS waterproof if you really wanted those underwater measurements. Some do that, but I've been at this a while and have yet to need more than surface measurements. Check out past posts by clicking this tag: #lux (need to be on the web view I think)
I would suggest more than a cellphone app in the long run though. Nice for now, but a $10-$20 dedicated handheld meter like my LX-1010B is better and almost a no-brainer. (And also works with the ziplock.)
Just use....live rock + protein skimmer. That's the basis you want to build from. (Not news, right? )
Since you already have the lights (obviously) I think I'd try to maintain a Leather + Fish tank. I'm thinking toadstools, Yellow leathers....lotsa good options. The demands they place on chemistry are small. Place them where the problem algae tends to grow and just make sure the tank doesn't run out of phosphates. Anemones may be another option for you if the fish population is compatible.
Other soft corals can work too, but most seem to have issues in my book....toxins in the paly's and zoanthids, for example. nth degree spreading in some of the star polyps. Etc. Leathers are nice since they still grow from a base (and stay put), and can usually be trimmed with scissors when they get too big.
My guess is that you have a co-bloom of some filamentous algae along with something like diatoms growing as epiphytes. It's common.
Probably too much light and too many nutrients into too new of a tank....nothing but space for algae to grow and ideal conditions for it. (I.e. immature tank)
Egg crate is too hard to clean too...you might consider switching to something easier.
No other filtration or media at work?
Can you also turn down the lights a little? Before you do, any idea what the current #lux or PAR levels are like?
It seems like what you're missing is a solid cleanup crew. Any change you have an herbivore fish in a larger tank nearby that you could "borrow"? Otherwise just get plenty of snails.
But what #lux or PAR reading do you get for a maximum?
I would let your nutrients stabilize around where they are. If they fall lower naturally, great, but don't force it except if you can reduce your inputs to the system. Let algae use it up and let snails keep your algae grazed.
Maybe too much light. Definitely too much filtration.
Also makes me question flow.
Your nutrient levels "ought" to be able to support pretty intense light levels...BUT...too little flow or too soft flow can be a real problem even in a situation with good lighting and good nutrients.
I'm sure it's useful to someone. Cool!
But as the PBAR folks (who???) agonize over that level of minuteness, we still have 90% of the folks in our little hobby not using any light meter at all. Not even a #lux meter, which can cost next to nothing and which can tell you almost everything you'd need to know for our purposes.
90% is much better than it was even 5 years ago, but the point still stands – wa-a-ay more folks need to have a light meter.
New tanks are rarely all that stable since everything from tank maturity to livestock load is usually in a state of flux.
Do both seem to vary normally, or do one or both of them seem to be always the same?
Check out all that past posts under that hashtag (or just run a search for posts with "lux" in them) and check this out as well:
They only run $10-$20, so it's an easy buy. Anything like the "LX-1010B" I have will do.