Sorry to hear that...that's awful.

Just a theory...

Shutting the skimmer off at night allowed the oxygen level in the tank to drop to deadly-low. Fish died....then the skimmer came back on to find a extra jolt of death in the water and foamed over.

Skimmers supply O2 to the water as well as remove nastiness. This is critically important at night when no photosynthesis is occuring. (unless you have an opposite-light-cycle refugium...which can help)

Once you are up to it, read this...

http://reefkeeping.com/issues/2005-08/eb/index.php

Sorry to hear about your skimmer problems and subsequent losses. This is exactly the kind of thing that prompted me to install a float switch into my skimmer cup over the weekend. I've had a couple episodes of my skimmer overflowing for no apparent reason (one time while on vacation leading to some nasty damage). I don't know if it's a BK thing because I get the same intermittent fizzing then skimming thing you described earlier as well. I'll never run a skimmer without a float switch in the collection cup again.

Don't bow out yet. Take it as an opportunity to install some new backup hardware - new toys are fun ;)

I've read numerous references that O2 is not strongly affected by protein skimming.

From the article you've referenced above:

Airstones and skimmers appear to be a very effective means of oxygenating small water volumes. Their effect on larger water volumes appears to be less. While the effect may be relative, the larger tanks and systems described here utilized powerful skimming or air pumps, and to gain an equivalent amount of oxygen as occurs in small water volumes would likely require air pumps or skimmers far larger than those commonly employed by aquarists. This includes data from a coral farm where very large commercial sized skimmers and high surface area/volume ratios failed to produce water even nearly saturated with oxygen at night with a heavy coral population.

Thanks untamed, I actually was just running the skimmer at night and not during the day to avoid low oxygen levels at night. However I did just figure out the problem and it was a result from low oxygen.

I remembered I did the final programming on my controller yesterday, what I wanted was the skimmer to act as a timer and only run at night but I also wanted it to turn off during a "feeding pause" because I would be feeding the corals more at night. In addition I wanted it to stay off for another 30min after the feeding pause ended. I used the programmable logic to to combine the timer with a delay on set to 30min and then all I needed was the timer to shut off during a feeding pause but I couldn't do this with the programmable logic. So I noticed a check box under the timer which said something like "active then feeding pause", now keep in mind that profilux language seems to be mostly translated from German so it's not always clear, I automatically assumed that checking this box will insure the skimmer will shut off during a feeding pause. Similar check boxes are attached to other processes and I've used them before with success.

Unfortunately I was wrong, by checking that box I told the controller to activate a feeding pause while that timer was active and for as long as that timer was active! So last night at mid-night, while I was sleeping, all my pumps turned off and 30min later the skimmer turned on, which overflowed with the higher sump level. The pumps remained off until noon today. The fact that this happened over night with all the livestock I have must have completely diminished all the dissolved oxygen in the display while the skimmer helplessly filled the disconnected sump with foam.

So Mr OM, you were 100% correct, it was an engineering problem. A problem resulting from the stupidity of this engineer who didn't check his programming which resulted in the death of very creatures I designed this tank for. I take full responsibility but the one thing that blows my mind is that the profilux will not allow you to set a feeding pause longer than 20min yet it will allow a timer to activate one for as long as you set that timer for. That is one dangerous check box, users be warned.

I think you mentioned that your clams spawned a couple of weeks ago...maybe that "stuff" also had something to do with your problems...along with the pumps being off and your skimmer not working very well .It all added up.

Ai ai ai Steve!! This is horrible news!! :eek: :(

Let me know if I can help you out at all. Remember, I'm only 5 blocks away. ;)

Go
 

this is a noob question. How do you measure the level of nutrient in your tank? How do you know if it is high or low?
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ASCARI

By nutrients we mean nitrate and phosphate specifically. In the case of phosphates, we can only measure inorganic (dissolved) phosphate. Standard test kits are not very accurate in the low range. I would use Lamotte, Hach, or D & D Merck. SeaChem and Salifert are two of the better hobby-grade (cheaper) kits on the market.

Go
 

Sorry to hear your lost.


What level nitrate is considered high nutrients?
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Marijuana sativa

Nitrate levels over 25 ppm will adversely affect coral health. Anything above 10 ppm will cause nuisance algae growth. I would shoot for 2 ppm.

Phosphates should be 0.05 ppm. Corals will be adversely affected if it goes above 0.10 ppm.

Nutrient levels on natural reefs are zero, but they are always bioavailable. Captive reefs don't have as much organic phosphate and nitrogen available due to a lack of plankton. As a result zero nutrient tanks are only suitable for sps corals. Good lighting and heavier feeding must also be implemented.