lduncan

Well Mg is the third most abundant element in the ocean at 1300 ppm so yes, it's probably worth keeping levels as close to that as possible. Layton

Around 100:3 Chloride:Magnesium, which is why I say go with Mg chloride, over sulfate. Layton

Absolutely, it's what I use. Been through boxes of it. Layton

Look for food grade at least. Magnesium chloride is used a lot in farming, and that grade (to me) is unacceptable. Epsom salts is Magnesium sulfate. Magnesium chloride is preferable to mag sulfate, as chloride is more abundant in salt water than sulfate, an skews the chemistry less. If you want to get technical you could use a balance of sulfate and chloride. Layton

Magnesium chloride. You'll probably need a fair amount (a few kg). I think that APS chemicals in Auck can supply it. They generally only do 25kg bags min. Layton

If your calcium is at normal levels, then baking soda added over a period of a couple of days. Mix with fresh water before adding to the tank. Use the calculator here to find out how much you need to add: http://home.comcast.net/~jdieck1/chem_calc3.html Layton

I think it means it's time for a bigger tank Interesting thing is that coral recruits (baby corals from spawning) are preferentially attracted to coralline patches to anchor and grow. Layton

I find google's index of the site is excellent, a little more useful than the inbuilt phpBB search function. The google option shows up on the same page when you hit the search button above. Layton

Thanks, found another company that makes controllers from that site: http://www.riffcontrol.de/catalog/ Layton

Ha, you don't want to add sodium metal to your tank, it might scare the fish as it bursts into flame wizzing across the surface of the water. Sodium hydroxide is what I use. Mixed with a little water into a syringe and into the aiptasia. Don't get the mixture on your skin, if you do, wash with PLENTY of cold water. And like Ira said, make sure you're reasonably accurate. You also only need a small amount to kill. I use around 0.1mL per aiptasia. Layton

Nope. There is no such product. You have to manually exterminate every one with a syringe. Layton

I tried it on my green star polyps, and they didn't even flinch. Still can't get rid of them!

... and so does the mash used to make normal vodka Layton

What's the polyp extension telling you though? It could just as easily be gagging and choking on the stuff for all you know. Once again, you can't infer much about corals based on looking at polyp extension. Layton

I hear bacteria like fejoa

The polyp extension / growth relationship is also related to water flow. The high the flow, the thinner the boundary layer around the coral and the faster diffusion can take place, meaning that corals don't have to extend the polyps as much to get the required elements to support calcification, or to remove waste. Layton

:lol: Contrary to popular opinion, polyp extension is not the corals way of telling you what suppliment to add to your tank. It's one function which polyps don't provide. Layton

Yeah I know what you mean. Just wanted an excuse to post that pic. It's in the wild, the Lembeh Strait I think. They have been introduced their by collectors from their natural home of Bangaii Island. Layton

Nope, colours are never the same. This coral is more purple and greenish than the weird base colour and yellow it is in the photo. Cause that's where the light comes from. ;-) Layton

Nope, like I said. I never notice this one growing. There are other acros in the tank which I do notice growing, so they must be growing faster than this one. Probably a medium to slow grower. Yip, this camera is a LOT better than the old one. I'm still crap at taking photo's, but it's easier to take better photos with this one. Layton

Well at night zoox are consuming O2 and producing CO2, so again it primarily comes down to respiration (in SPS) and gas exchange. Although like I said, you could not guarantee that, the coral could be doing the equivalent of puking or choking and you couldn't tell the difference just by looking at it, but regulating respiration is the primary function. It apparently in some corals it can also be an adaptive instinctive behaviour related to retract polyps during the day to prevent predation by corallivorous fish. Just another point on the feeding thing. If you scraped all the tissue of all your sps in your tank and put it into a little vial, you would not have a lot of living tissue, maybe a few grams at most, in terms of food, that is all the tissue you would be feeding. There is more than enough "food" in the tank to support that amount tissue. You're not going to starve them. ;-) Layton

Probably better, but still can be misleading. :lol: Bleached corals can be colourful and stressed corals can grow faster than usual :lol: But in general it's probably a better indication. Layton

In a word, no. SPS developed their small poylps for the reason that feeding (in terms of polyp prey capture) was a marginal function. Respiration is the goal. It's all about surface area. SPS are overwhelmingly branching type corals (high surface area). Having small polyps means that when they are extended, they don't shade the base tissues, which has higher zoox density. Why would the polyps want to extend then? Well for calcification. This demands CO2, and with zoox using CO2 to produce their sugars etc (by photosynthesis), they are in competition with the coral. By extending their polyps, sps can gather the more CO2 (by gas exchange) to support calcification and photosynthesis at the same time. Sounds pretty good to me. Layton

SPS polyps aren't primarily used for feeding in that way. Respiration is the main function of them. That's a common misconception. They could just as easily be "choking". Don't get me wrong, i'm not saying there is anything wrong, just that drawing conclusions from polyp extension is near impossible due to wide variety of functions they have. Layton

These guys mustn't have got that memo Layton