lduncan

The distance from the bulb to the water is important, but that is generally determined by the type of bulb. Also the outer diameter is important, but not necessarily a purchasing decision. You can adjust for larger diameters by reducing flow, and vice versa. Layton

I think you've asked before. They use a PL-L style bulb which is nowhere near as good as the GPH t5 /t6's They try and compensate for that by using the helix to try and maximize exposure time. Personally i'd avoid those helix style ones. Much harder to clean. And often they are just trying to compensate for poor bulb performance. Also note that the Deltec UV's are re-branded RuWal units. So RuWal can be added to the list of "known good" UV units. Layton

I've had another PM basically asking what the difference between different brands are. I'll try and explain what makes a quality UV unit here. What's the difference between a good UV unit and a crap one? Basically the difference between the units is the quality of plastic, and seals, and the type of bulbs used. UV can be hard on plastic, it breaks it down much like it breaks down organics in the water (splitting those C=C bonds mainly). Viton seals hold out better under UV exposure. UV will tend to turn plastics brittle over time. Quality plastic will prolong this. Bulbs are probably the single most important part, to be really effective you need a unit which uses GPH t5 / t6 tubes, with pure quartz envelopes. Standard glass will block the majority of the useful UV spectrum. Glass bulbs are common in smaller, cheaper brands. Some UV units are really made for "clarifying" which is more of less useless for what we want it to do. It'll "clarify" a pond of algae, but won't do a lot more than that. The brands I recommended above, I know use the right type of bulb. There may be more, but they are the ones i've personally looked into. Virtually every UV unit uses pure quartz sleeves. Also, don't bother spending extra money on models with a sleeve "wiper", they are a waste of time. Where do I get one? Aqua UV - stocked by Marine Depot (make sure you order the 240 volt version) Emperor Aquatics - can probably be found online too, but Marine Depot don't appear to carry them. Deltec - shops that are meant to stock deltec gear, or ask reef. Layton

I've had several PM's recently asking about UV. Sizing, types, brands etc. First a couple of threads on uv which hopefully clear up some misconceptions, and offer a different point of view: My observations - white spot, UV, skimmer uv zapper or not???? U.V. UV, why and what for? Sizing: Basically the bigger the better. You can't OD UV. I would recommend starting with a 40watt as they tend to be "modular", so that if you upgrade to a larger tank, you can tidily gang up a second one to give 80watt etc. Also, UV tubes efficiency diminishes rapidly initially then plateaus over time. If you "oversize" the unit, and run lower flow rates through it, you can save significantly on bulb replacement costs. Running a 40 watt factoring in a 6 month bulb replacement cycle (longer if you "oversize") costs around $20 a month Important Features to look for: High Output GPH t5 / t6 style pure quartz bulbs. (It DOES make a difference) Recommended Brands: (Unlikely to find suitable brands "off the shelf" in shops here unfortunately) Aqua UV Emperor Aquatics Deltec Layton

It's been that way for years. It's because the way it works is difficult to control. There were product reformulations shortly after introduction to the US market after they found that some parts killed corals, even when used as instructed.

no, the orange thing is the anal sac (yes that's the technical term )

Looks like a Longspine urchin (Diadema setosum)? Heaps of info around on their algae eating habits. They are used as an indicator species in the Caribbean for reef health. Here's a pic of mine. Came as a hitchhiker. Just popped out of the rock one day. They grow VERY quickly over a month or so it got to this size: Layton

Yeah, coralline algae

Nitrate often gets blamed for the problems which phosphorous actually causes. Phosphorous is the one to worry about. It's the one which kills stoney corals.

I'd say the opposite myself. A sulfur denitrator is a DSB in disguise (with slightly different dynamics). But basically it provides an environment for SRB (sulfur reducing bacteria) which happen to be bacteria which also reduce nitrate, and are also the ones responsible for the black patches which form in DSB's (iron (and other metal) sulphide deposits). As such it has some traits of DSB's too, like heavy metal and phosphate accumulation. But personally, i'm not a fan of methods which rely on bacteria to process waste, and increase the bacterial populations. I prefer methods which remove, rather than process. I would favor UV over sulfur reactor. Depends how often you want to empty the skimmer collection cup. I've just had my UV turned off for 3 weeks, and turned it on again this week. I've got a AP902 (around 800L tank volume), without UV it fills the collection cup every 2 or 3 days. With UV, it fills the collection cup every day. http://www.fnzas.org.nz/fishroom/my-obs ... 16491.html If you're buying a UV i'd get 40 Watt min. Decent size, and allows for future upgrading. Make sure it has a HO quartz bulb. The bigger the better. Layton

A sulphur reactor will reduce nitrate effectively. However, I would recommend UV as a good option for reducing nitrate and phosphate (so long as the skimmer can handle the increase in output), it also eliminates the need to run carbon, controls parasites (if that's an issue) etc. My philosophy is when you're trying to reduce nutrients, is focus on getting stuff out of the system. People often look for things to dump into the water to solve these problems, which just adds to the nutrient pool. (not to say it won't work, but I think it's better to increase the efficiency of the existing processing) Layton

I guess only specially selected people get to see the "IP" button on posts. ;-) I wonder how the weather is in Sydney today?

Juvenile Ctenochaetus striatus? Looks more Ctenochaetus sp than Acanthurus sp to me.

So? If only you knew what I do for a job (and have done for the 10 years) ;-)

It looks similar to a turbelle PH. Some models are controllable other aren't. I wouldn't bother moving all the water. Luck there is only a handful of livestock in it. Put them in a polybox, the rock into a bin submerged in water. And you might wan't to take the opportunity to clean the sand out ;-) Layton

:roll: Never made a typo before wasp?

I'm not comparing myself to them in that way wasp. Just explaining my philosophy on things.

... and i'm still trying to get that metallic taste out of my mouth :lol:

you'll ruin my reputation. Winding people up? I don't post stuff on here for the entertainment value of winding people up. I can think of hundreds of things i'd rather do for fun In the long run, people appreciate a bit of reality, rather than "people pleasing" BS. Which is why I find that analogy someone made about their child so wrong. People should be encouraged to speak their mind. Rather that, than be too scared to think and speak freely (how many world change people shut up just because someone said they were crazy.. Galileo? Da Vinci? Edison? Eistien? ...?). At least that's what i've found. Sure i'll say things that people don't want to hear, but it's not for the sake of argument or sadistic entertainment. It's for discussion, getting people to think about why they do something the way they do. Occasionally, I say what other people are thinking, but are too afraid to post. ;-) Layton

With a blue tang and power blue tang, adding a sohal may be a case of three's a crowd. Layton

Around 15cm head to peduncle. I've found that clowns seem a little more aggressive than sohals. But that just based on individuals I have owned. Who knows I may have an unusually mild sohal, or overly agressive clown Interestingly, the sohal and clown got on well in the same tank never any sign of a stand off between them. All in all it often comes down to trial and error. People would say putting a raccoon butterfly into a reef tank full of acro's is crazy, but i've never seen mine even look like touching a coral yet.

I just re-colour calibrated my monitor to check it wasn't my screen. But it still looks pretty blatant photoshop to me :-? Anyway, i definitely agree with the whole "hands off", keep it simple, less is more approach.

looks better in person that in the pics too

:roll: It's so bad it's comical. I'm not commenting about the tank. I don't know what it looks like. But I can spot bad photoshopping. That's about as bad as any i've seen. So bad, i didn't even read the thread, because they were so distracting.