Biofilter dry out experiment...

Hi all,
Wanted to share an experiment with you. I was curious about the bacteria in my bio filters and Drying out. I read an interview once where Dieter Untergasser said that fluke eggs would die if they dried out for 3 days. Sounded like a reasonible thing but 3 days of being dry would kill the bio filter by most accounts. I wanted to test the biofilters response to drying out. I had a hunch that the bacteria might go dormant or produce resting spores of some sort.


I took my 55 gal tank, drained it and let it dry. I pulled the hydrosponge 4 and the aquaclear 500 sponges from it, both very well cycled. I gently rinsed them and let them air dry for a week. I wanted to make sure they were dry , so I placed them next to the wood stove that heats my basement. Let them dry for 7 days.

I filled the tank, and replaced the sponges, I then took 5 mls of clear ammonia and spiked the tank. I tested the ammonia and it was off the charts. I tested daily for 3 days, by day 3 it was gone, I added another 1ml and tested, and again it was off the charts. By day 4 it was gone!

Seems the biofilter bacteria does go dormant, or produce spores and reactivates pretty darn quick! I think I'm going to dry a sponge and keep it for emergencies.

I could use some independent testers to validate the experiment? Anybody out there got a cycled tank they are not using?  ;D
take care,
al


addendum...
After I refilled the tank, I added the 5 mls of ammonia, it took 3 days to be consummed. I then added another ml of ammonia, and it was consummed in a day. Total time for the sponges to reactivate here seems to be about 4 days. from what I have seen most should be good as gold in under a week!

Hi Al,

Sounds like the bacteria that convert ammonia to nitrites were definitely present in your dried out filter.  My question is whether the second kind of bacteria--which convert the toxic nitrite to nitrate--were also present.  Did you test for nitrites during this process?  This is important because it is usually the growth of this second kind of bacteria that is limiting in getting a tank fully cycled.  They always seem to take longer to get established and up to full capacity than the ammonia-eating bugs.  Therefore if you found these second bugs also survived drying that would be an especially important finding!  You could probably start a very successful business of selling dried out cycled sponge filters!

Good luck,

Pat

Hi Pat,
  The thought had crossed my mind ;D And yes Nitrate reducers are  present, They kicked in  a day latter  though. I did not test for nitrates but I would assume as a product  they would  be there last.
 Check out Gary's experiments on freezing in the main area if you get a chance.
  Take care,
al  

Fascinating.

I've just started my tank with a dried out cycled sponge filter and filter squeezin's from a planted tank.

Well, I may run a test. I've got a dry biowheel and a bare tank to try it on.

UPDATE-- I've added 16Teaspoons of ammonia to a well scrubbed and bleached 55 Tall tank, filled with tap water, heated to 90 degrees, running a Penguin 330 that was well scrubbed after being dry for about a year, and using 2 old used biowheels that were never really cleaned much after use (Brown bacteria film peeling off in tiny flakes) wheels are at least 9 months dry, maybe more.

Ammonia is at about 3ppm first day, not tested 2nd day but brand new Seachem Alert says still Toxic. I'll let you know if anything changes.

June 26-- Update... I filled up the 55 Gallon tank in the garage on June 19th and added 16 teaspoons of ammonia and the ammonia level seemed to be near 3 or 4 ppm (old test mateial and no color chart, had to look it up online). The Seachem alert said Toxic and was maxed out, deep purple.

Seven days later, the ammonia level is at about 2 ppm and nitrates are at 20ppm. I don't have a nitrite test. I've run out of time to conduct this experiment as I need to move the tank inside and transfer the baby discus to this tank.

I admit this was a flawed test, but I think it certainly shows potential. The tank had been well cleaned (bleach, vinegar, CLR) and dry a long time, the heater was nearly new, in a tank for a few days then out and dry for a week. The Seachem alert was moved straight from the baby tank to this big tank but it shouldn't have carried much bacteria on it. Certainly not enough to affect such a big tank. The filter had been well cleaned after being dry for a year or so. Only the biowheels could have carried much bacteria, they had been dry for quite a while, at least 9 months I'd guess.

Interesting that the ammonia was not totally gone but that I had nitrates so high. My tap water never has nitrates, the few time I've ever tested, the water reports show that we don't have nitrates. This is sort of the reverse of normal cycling where ammonia needs to go to zero before nitrites are processed into nitrates. I may have had nitrite consuming bacteria endure the dryingout better than the ammonia consuming bacteria, just a wild guess on my part though. 16 teaspoons seems like a lot of ammonia to get 55 gallons of true tank volume to 3ppm, so maybe it was actually higher than that at the start. I really need to replace my Master test kit.

Sorry that I was so lax on the experiment. It would be great if someone could do this again with more control, daily testing and so on. I do think the ammonia would have been gone tomorrow, it was dropping very fast in the last two days. The container of tank water I saved during the day as I worked on preparing for the tank move did show zero ammonia by the end of the day according to the Seachem alert. At that point, a second dose of ammonia and careful tracking of tests might have shown how close to complete the cycling was.

Meanwhile, I've got the new tank up, with lovely blue insulation behind it and white foam insulation under it, the biowheel and heater running and in the morning when I'm pretty certain the pH has settled I'll move the baby discus.

Interesting expirements!