lduncan

Unless of course you happen sell potassium supplements ;-).

Why the interest in potassium?

Can you backup this "fact"? Using one, doesn't make it more accurate than the manufacturer say's it is, nor does seeing one. Accuracy +/- 0.04 mg/L +/- 4% of reading +/- 0.01 mg/L electrical noise. It uses exactly the same chemical reactions as Salifert (and virtually every other brand) phosphate test kit. No, not me. There was an article in ReefKeeping recently which talked about meters, resolution, and accuracy, and how to interpret the readings you get from them properly. I don't know what makes you think they are more useful than a standard hobby test kit? I don't have to use one. I don't have to see one. All i have to do is read the manufacturers specs, and know how it works to have an opinion on it. I'm not attacking it. Just making an observation on how useful it is relative to other methods. The fact is, that it's no more useful than a standard test kit. We've been through this before. Just because you think it feels more accurate, it doesn't actually make it more accurate. Layton

Yeah, King street, over the river from the Crown Towers. Actually, the one redeeming feature I remember were the jellyfish tanks. They were interesting.

I went there a couple of years ago. It was xxxx. I was highly disappointed. I never bothered going back my recent trips over. Layton

Exactly. Unfortunately that's all you really have to go on, test kits are effectively useless for letting you know how good your phosphate levels are. You've got no choice but to look at indicators in the tank. The alternative "proper" testing is just not practical.

that's true. Test kits (including the Hanna Meter) can never tell you how good your phosphate level is. It can only tell you how bad it is. Wasp was implying that his "proper equipment" (the hanna meter) is somehow more useful than a test kit. The fact is the Hanna meter is no more useful than a "hobby kit" I've said it, Hanna themselves say it, even "experts" have said it. To call a Hanna meter "proper equipment" relative to normal test kits is not exactly fair. I'm not saying that you need to know what your phosphate level is, it's not practical. Just know that these test kits / meters aren't even in the ball park for testing extremely low levels of phosphorous. For a start they don't even cover all forms of phosphate.

What for?

Hanna meters aren't proper equipment. :lol: You need to spend a few 10's of thousands more for proper equipment. ;-) 0.03 ppm isn't extremely low, so saying phosphate levels < 0.04 are extremely low, isn't even close to being correct. By that logic, I could say that phosphate levels < 1,000 ppm are extremely low, but does that make sense? Not to me it doesn't Kind of important to at least mention that this is actually caused by bacteria. He didn't even write the word. It seems strange that you wouldn't. Saying it's just from localised low pH makes it seem like you may have some control over it happening, but you don't really. Having said that it's on the right track. Layton

WOW a whole article on phosphate without a single mention of bacteria While I can see the general gist of the article, there are a few inaccuracies/oversights in the details. • 0.04ppm is not extremely low. It's actually several orders of magnitude higher than what would be considered extremely low in terms of corals needs. • Any phosphate with is precipitated with kalk is far from inert. It's still available to bacteria, and they will happily use it. What it does do is become undetectable by test kits (which only measure orthophosphate). This can give the illusion of phosphates being lowered. • There seems to be a tone that this precipitated phosphate is released back into the water through purely chemical means. What's happening is that bacteria are the ones which remobilise this precipitated phosphate. One of the methods they can use is to create micro-environments, where pH may be lowered significantly within a biofilm. Layton

I'm not particularly interested in bacteria/parasite kill rates. It can be a nice side effect, but i don't think it's actually the main benefit of using UV. The photochemical reactions with organics is more important, and I think has by far more effect on the system. Splitting those C=C bonds (plus a few others) is what you should be interested in. Layton

Lehtola MJ, Miettinen IT, Vartiainen T, Rantakokko P, Hirvonen A, Martikainen PJ.

Impact of UV disinfection on microbially available phosphorus, organic carbon, and microbial growth in drinking water. Water Research, March 2003

I though I explained it in general terms? This was the mechanism presented in the paper I found a while back: Knowing that amount of bacteria in a cycled tank is not constrained by reproductive limits, but by food limits. I'm tying to find a link to the study, but it was hard to find then, and proving hard to find now! Most of what you find is how bacteria directly exposed to UV are mutated, they ignore what happens to bacteria in other parts of the system which are not directly exposed to the UV radiation, but are exposed to the other effects of UV (mostly the molecules created by the UV splitting C=C bonds in large organics). The study I found looked at both, and specifically similar denitrifying bacteria species. It pretty much corresponds to what I saw in the first couple of weeks after turning on the UV. Makes sense really. Does a better job than carbon. Doesn't release phosphate like carbon. Boosts skimmer output. Reduces large (often toxic) organics. Turns these into food which is easier for bacteria to use. Leads to more bacterial export (depending on tank setup) Only downside? Maybe the maintenance every 6 moths or so? Other than that, from my point of view it's all positives. Layton

The website looks good cracker.

This is a common question / misconception about UV: In fact, using UV often increases total bacterial populations, by providing a more available food sources. And it does this without adding to the total pool of DOM (unlike systems such as zeovit). It takes existing large organic molecules and splits them which often results in molecules which are easier for bacteria to use. So who cares if you maim a few in the process, they need to be skimmed anyway, dead, maimed or alive. That's pretty much my point. Layton

no, that's kinda the point. UV / no UV the skimmer still removes them. So what does it matter if the skimmers skimming maimed bacteria or live bacteria. It doesn't matter.

... so you don't want them in your tank, you want them in the skimmer. and UV helps with that. A skimmer will skim UV maimed bacteria as well as it does non-zapped bacteria.

Doesn't a skimmer defeat the purpose of trying to cultivate 'good' bacteria through practices like adding vodka and bacterial cultures? Why do you want all that bacteria in the system? Layton

If you're buying a new one, I'd stick to the brands mentioned: Emperor Aquatics, Aqua UV, or Deltec They use GPH t5 / t6 style, pure quartz lamps, which are more efficient than the PL-L style in the Aquamedic ones. Layton

I would say yes, smaller is better than nothing. But the key is the flow through it, it needs to match the wattage to get the required exposure to do anything useful.

If you look hard enough on the internet, there is an interesting study in the Baltic where the found that while UV reduced water bourne bacterial counts. The total population of bacteria in a system was increased, when using UV. The also specifically mentioned an increase in denitrifying Pseudomonas species bacteria. Before I had UV, my nitrates had been hovering around 5 for a year or so. A little over a week or running the UV, the skimmer output increased dramatically, the rock started "bubbling", more detritus was produced, and nitrate was undetectable. I assume this was from boosting the bacterial activity within the rock -> more detritus -> higher skimmer output.

I run a 40Watt HO, and I wouldn't be without one. Absolutely worth having. No need to run carbon (which eliminates another source of phosphate). Increases bacterial activity (specifically denitrifying bacteria), by splitting large organic molecules into smaller ones which bacteria can process more easily --> Increased skimmer output and lower nutrients. Plus the side effects of parasite control. Just get a high quality, high output one. I would recommend the Deltec one, it's competitively priced, but are much higher quality than the cheap asian imports. Emporer and Aqua UV are also good brands to look for. Layton

I would say absolutely worth investing in... But not at the expense of other equipment. But not specifically for parasite control. They make a significant difference in nutrient export. They can make a significant difference to the output of a skimmer. Layton

Still ok to use. But annoying, and the noise will most likely get worse with time.