Paul seeing that brewing system put a smile on my face! That is one cool setup you have there, although your dog dosent look too impressed, it needs a caption saying 'I want to go in and see my owner, but that room scares the hell out of me and I think I will die if I enter'! Unfortunately now I dont do much brewing because of space in the current house, we are waiting to move hopefully this year to a place with a few acres but at the mo, since kids came along, all my old space has been taken by their stuff, and I am not allowed to have 'dangerous stuff' like 10 gallon kegs of boiling water anywhere :-( I still have a load of old copper stuff I made years ago, including this giant mash tun thats about 50 or 60 gallon, with a circulation pump powered by a drill, and steam pressure lance with a boiler made from an old keg. I also need to get brewing again soon because I cant drink normal beer now made from barley so I need to get working on malting my own corn or oats or something.
Anyway back to tanks (for now). Re the ammonia photo, its hard to tell, since the way a camera percieves color is not always going to be the same as the eye because of different spectral sensitivities of the 3 color sensors in the eye / camera. But if the photo looks like it does in real life, I dont think it looks like theres much ammonia there to me. I think you can increase the sensitivity of the ammonia test somehow, by adding alkali or something, or maybe thats just the intank sensors that can do that, not sure. But since I dont test for ammonia myself its hard for me to advise about that. Maybe Randy could provide more info re the ammonia photo.
Re how long to go without N and P, I think since our test kits only measure to tens of ppb at max, its hard to say. On the great barrier reef (gbr), inorganic N is sometimes below 1 ppb, organic N around 70 ppb, inorganic P around 3 ppb and organic P about 3 ppb too. It varies, not sure if I posted this link:
http://www.gbrmpa.gov.au/__data/assets/pdf_file/0004/7690/MMP_AIMS_August_2008.pdf
Around page 20 onwards there are tables of detailed reef water quality parameters. Really interesting. So if corals can survive and thrive at nute levels below what we can test (IE read zero on our test kits) then its not possible to say how long a coral can survive when our kit reads zero. But my experience was that different corals lasted different times. My hammer survived for months in an environment where other corals perished in weeks for instance. Others lost color but hung on just about for a couple of months. My nutes were probably gradually declining because I thought I had excessive nutes (before I got a low range test kit for phosphate). So I fed a few milligrams of flake a day to a 55, while dosing 1 ml vodka a day. Now I realise my nutes were actually low, must have been gradually declining as stuff died off and the skimmer gradually removed all traces of nutes. I dont know what the levels got down to of course. Probably pretty low, like a few ppb or less, with very little organics in the water too.
New frags of acro had no polyp extension as soon as I put them in my tank. But they didnt die for a few weeks.
Getting back to the GBR link, you can see that organic nutrients are considerable, especially nitrogen (70 ppb). So that suggests that corals can be happy with low inorganic N but medium levels of organic. So if you feed blended fish (clam, squid etc), the blending is going to release some of the organics to the water (dont strain the food imo). This is why I am thinking feed instead of add inorganic nutes. Food will eventually break down to inorganic ammonia, N and P unless you do carbon dosing though, which is why I think you should dose carbon (vodka, vinegar, all the same IMO, maybe subtle differences but they all provide similar effects and I have no idea if any is better). Carbon dosing will keep the tank ammonia and N and probably P under control I think. You can use a skimmer or GAC to remove some of the bacteria if your glass is getting too dirty too quick, signifying organic nutes are too high. From the GBR data you can see that particulate P and N are available too, one form of which is bacterial flocs, which is what is formed when carbon is dosed in our tanks too. Its slightly confusing because organic N and P in the tank water can come from both blended food, and also from bacteria in the tank created when you dose carbon. But it all feeds corals.
Re the complexity btw, IMO I dont feel you need the fish and shrimp. I think that bacterial action will do what you need, although as I say I do think you need carbon dosing too. But perhaps there are several ways to do this job. One might be to have a fish which provides a bit of ammonia, but the way I see it, if you have ammonia you need to have bacteria to get rid of that ammonia, and without much substrate that might be borderline. If you dont have a fish and feed the tank the ammonia will still be produced I think, by bacteria instead. But these are tougher bacteria which dont need as much substrate or as delicate a balance of conditions. So you could find you have enough bacteria to make ammonia but not enough to get rid of that ammonia. So if you want to try not dosing carbon, I think some kind of bacteria filter might be good, very coarse sand perhaps, maybe a cannister filter (never used myself though). But my preferred method at the moment would be carbon dosing as I say since the bacteria are aggressive, comparatively tough, and provide food, plus we all know that carbon dosing seems to have positive effects on coral tanks, even if our theories about why are wrong.
BTW if the tank or equipment is suspect did you think to do a triton test for metals etc? Not sure how much you want to spend but if for instance something electrical was leaking metals like nickel or copper, or the tank had a residue from previous problems, triton would show you wouldent it.
Does the glass ever need a clean btw?
FWIW I am getting help from Randy in another thread for an idea I have for the moment which is vinegar and blended food combined into one diy frozen cube, or perhaps as its looking like now, a paste with blended fish in vodka, which is balanced in terms of carbon : food ratio, and which I can either throw a single cube in every day to deal with both carbon and food, or perhaps even keep at room temperature and dose with a persitaltic pump, if the food is preserved in vodka.
