fishless cycling

[asparagus]

Hi Guys,
Im leaving for a week vacation on 12/4. I had planned on having my new 29 gallon tank cycled (fishlessly) by then and getting my fish right when we get back. I had also planned on getting a betta for myself and my daughter then in a 5 gallon filtered tank (for each of us). I was going to use some water from my cycled 29 gallon tank for the 2 five gallon tanks. But then a thought struck me- will the tank "uncycle" over the week while Im gone and am not adding any ammonia to it? Do I have to do a water change when I get back? If I take out about 8 gallons of "cycled" water for the 5 gallon betta tanks, do I have to start the cycle again for the 8 fresh gallons Im putting back in?
Assuming the tank cycles before we leave, can I just leave it running fishless and ammonialess for a week? What should I do to it before I add the fish?
Thanks!
Asparagus

 

[WILDER]

You could put a prawn in while youre away.

 

[daza]

The tank will uncycle if you leave it for a week without adding ammonia I'm afraid. Some of the bacteria might remain and make recycling after you return easier - but maybe not.

It could also help if you bought an automatic feeder, and then the food being added in the week will decay, produce ammonia and help to keep the bacteria alive. I'm not sure how much of an effect this will have though. Others may have a better idea.

Don't worry about doing a water change until the tank has fully cycled and you are going to be adding fish a day or two afterwards. Once your readings indicate the tank has cycled then add some more ammonia to make sure, test it has gone after 24 hours and then do a water change (50-70% maybe) - enough to bring the nitrAtes down. Check the water parameters the next day and then add the fish.

I also wouldn't bother putting the cycled water into the Betta tanks. A better thing to do would be to place some gravel in a stocking and put the stocking in your 29gal when it is cycling. Once the 29gal is cycled there will be some bacteria living in that gravel and that will speed up the cycling of your Betta tank more than adding cycled water I believe (apparently the bacteria don't live in the water itself). Better still would be to add extra filter media in the 29gal and then transfer that to the Betta tank to help speed up the cycle.

 

[asparagus]

If I just added a prawn before I went away (thats a shrimp, right?) would it produce enough ammonia? Id still have to set up a feeder, right? Im thinking maybe since I was going to start w/ platys- going and getting 3 of them a week before I leave and then getting one of those feeder pellets for the week? What do you think? I really really wanted to be able to play with my tank when I get back from vacation.
Should I put the whole 5 lbs of gravel in the stocking inside the 29gal cycling tank for the bettas? That sounds like the easiest thing to do at this point...Or just a handful will be enough?
Im getting nervous about all this now!
thanks for the ideas so far!

 

[WILDER]

I would add all the gravel now, I wouldn't add any fish if your'e going away, I would wait till you get back.

 

[sylvia]

Prawn as in one of the shrimp you would eat (dead) It would be enough to just add a prawn or lots of fish food to last the week I wouldn't get the fish before leaving cause you realy need to be there to monitor levels when you have fish in a cycling tank - incase they need a water change to keep them alive! Those feeder blocks have a bad reputation and contain little nutrition - a lot of the stuff they are made up of isn't food and will dessolve and make your water harder quickly. Some brands work better than others though. Automatic feeders are generaly better for feeding fish though controling the amount fed is tricky and they can get stuck... (this would only affect you if you had fish BTW this last part about the feeder was somewhat off-topic)

 

[asparagus]

So a dead shrimp from the grocery store will produce enough ammonia to keep the tank cycled? (sounds pretty gross, but if it will work!). Should I get shelled ones? Cooked or raw? (I dont really eat them so Im not sure how you buy them- Ive seen them in those rings with the red sauce in the middle).
Should I put 2 in?

 

[WILDER]

Frozen prawns just put two in the tank and it will keep your tank going.