.

This has the potential of becoming a good discussion if the flames can be kept out of it. :wink:

I am going to stand behind my original statement because it has the accumulated weight of scientific evidence behind it.

When you speak of more surface area you seem to be looking at the reverse of what is proven to be true. In a bubble rising to the surface you have a gas to water area. That is opposite to the surface where you have a water to gas layer. Thus no meaningful gas exchange can occur.

I will give you one thing though. The bubbles bursting on the surface will increase agitation thus more oxygen will be taken up in that area.

Anyway without appearing to be a flame, that is the way I understand it to be from extensive readings. OKAY????

Ok with out flames intended Bob, elplain to me the difference between a gas to water layer, and a water to gas layer?

at both points you have difusion going on between the air and water.. the advantage with the bubbles is that it is moving thus exposing its surface to new unsaturated water at all times.. with the water surface at the tank with out agatation it becomes saturated and stops.. with agatation you are breaking up the saturated level and exposing water with lower O2 levels to the air.. same thing that is happening in bubbles by virtue of them raising..

if you want another thing to think about look at how a skimmer works.. it makes a lot of bubbles throught which with the aid of a long contact time with the water, organics and other stuff are pulled into the layer around the bubbles. also at the same time O2 is being adsorbed into the water. because the level of air to water is very high in a skimmer (some aproching 50% or higher) it is like taking a blender and agatating the surface of your tank.

I don't mean to sound like a broken record but some of the stuff WE used to think was pretty silly.. why did we beleive it.. because some one sait it was true and it worked for them.. (mind you most of them made rediculous clames because they were getting paid for endorsing products.. which we never knew back then either.. )

Steve

I am afraid I can't add any more to the discussion. :shock: I am stuck on what I believe is true, and nothing said changes my mind, so I better leave it alone. :wink:

Doug
[Too bad there's no Hairy Mushrooms]
If you want some, I can bag up some various stray types from the mushroom factory if you don't mind attaching them. I think there is green/brown hairy, olive green, blue/green and maybe some blue tonga. The red ones are too difficult to get a hold of. They all seem to magically wander to a SPS sooner or later except for the blue. One on the birds nest, one on the purple tip acro, one on the yellow scroll etc.. Any good ideas of convincing them to go somewhere else :?:

kari

I think a good O2 test kit will resolve whether a tank is well oxygenated. I do believe strongly that my protein skimmer is the only reason my tank is at about 100% saturation (Other devices would work too but I don't use any other aerating devices).

Here's a couple of O2 saturation tables for salt water. My test kit shows a level of about 7 (+/-) at 25C.

http://ourworld.compuserve.com/homep...S/Oxygen-1.htm

http://www.emersonprocess.com/raihom...ers_200208.pdf

I do know that before I added the protein skimmer (when I started the hobby 1 year ago), I was losing fish like crazy from disease or stress over a week or 2 even though I was adding fish slowly (and replacements of the same fish would die too. Others like clownfish had no problems at all). At that time, the tank was agitated with only a powerhead at the surface and an internal fluval filter. There was a lot of water movement at the surface. I tested for Ammonia, Nitrites, Nitrates, Phosphates, etc and everything was near perfect. I couldn't figure it out.

Then, I installed a protein skimmer and then I noticed my replacement fish all started to survive. I thought ok, maybe its because my tank is more stable now or maybe it was just bad luck or maybe it was the ick that killed them before. Then, an event occurred one day that convinced me that my fish were dying from reasons indirectly or directly from lack of oxygen. One night I turned off the skimmer (so I can sleep better since the skimmer was noisy) and the next morning, my O2 loving fish was laying on its side gasping for air. It looked like it would die within minutes. I plugged the skimmer back on and within the hour, my fish was rejuvenated and is still alive with me today after 9 months. This does tell me that my tank is overstocked, and that some fish require higher levels of O2. But it also tells me that the skimmer does a better job of aerating my tank than the powerheads (w/o venturi) at my water surface. Nowadays, my fish still gets ick once in a while (after a stressful water change) but this time they survive and it goes away on its own.

This is my story and it might not be related to any of you who has lost fish but I do suggest getting an O2 test kit and just eliminate that as a cause. I wish that I did test the O2 level of my tank when my fish were dying so I could document what O2 levels are bad. It probably might have been useful to know which fish started dying at levels of 5 or 6.

One thing that I can't figure out is if there was a gas exchange between bubbles and water wouldn't the bubbles disappear given enough time? What about the surface tension of the bubble? Would that not act to prevent this? (theseare non-flaming questions :) ).

Ross, if you can keep the bubbles under the water long enuf they will dissapear.. unless the water is already saturated.. then you will be at a equilibrum.

Steve

Ross, just curious. Do you have a skimmer ? My thought is it isn't the cause of the losses you've incurred anyway. However, a suggestion that perhaps it is an O2 defeciency is a valid one and deserves consideration. We all know no systems ever function or react in the same way. Hell, I've only got two tanks on a "full time" basis and both tanks undergo changes and catastrophies separately. Both tanks are set up virtually identical, obviously with the same water source etc. but there are too many variables to determine what works and what doesn't. Sure there is basic chemistry, biology, physics and all that mind boggling "mumbo-jumbo" that's always changing. It's those damn variables I mentioned previously that make input/recomendations from people, all over, so valuable a tool in solving a problem. I'm not directing this "lecture" to you Ross, nor anyone for that matter...this just seems to be "snowballing" and things are goona' be said that might be better left as thoughts...

I was thinking last night Ross of your situation and something came to mind...it's a long shot like the O2 concern... you made some DIY live rock ? Can something be "leaching" still from that ? I've read very little on the whole concept. It is unfamiliar to me but...? How are the inverts. doing ?

Finally, life is good... :wink:

Oooops. I see ya' mentioned you are skimming.

Doug yes I do have a skimmer. It is an emperor aquatics skimmer rated for 150 gallons and removes lots of brown goey stuff( it is a bit small but I do have a deep sand bed). The fake rock are from a rather tried and true recipe. They are made from aragonite, cushed oyster shells and concrete (1 part concrete, 1 part aragonite and 3-4 parts oyster shells).

The trick is to cure them. I cured them for 5 weeks in fresh water (with frequent water changes and ph reducer) until the Ph remained constant. I then put them in the tank and they had another 5 weeks before anything was added.

Mostly it was just the first shipment of fish. I have 1 left and it is doing very well. It has stopped breathing so fat and is now firmly in charge of 1 side of the tank. My wrasse and clown fish are now doing very well and their overall condition has improved (especially the clowns).

The inverts are having problems. Each of them have started a molt and seem to have problems shedding their skin. In this state they seem to be prone to attack and ... well ... I am curently trying to figure out what could cause that. It has happend to all of them.

Thanks for the tips...and for sure no lecture came out of your post :)

Ross, I apologize if you mentioned this info already, but, what do you keep your salinity/SG at, and just for curiousity what brand of salt do you use? How often are the water changes at the moment and how big are they? Oh and what are you using to measure your SG?

Not promising the answers to these questions can give me an "aha" type moment, but it's worth a try.. :)

I'm rather stuck on what you said about the crustaceans having trouble molting. This seems unusual to me. One time, I can pass off as an anomaly but not when all are having problems. Maybe there is too much iodine in the water, or not enough (iodine is apparently a crucial element needed for triggering molting). It sounds like they might be molting prematurely, or perhaps molting too late somehow.