My new 120 has been cycling for about 3 weeks. I have about 100lbs live rock, 80 lbs sand, 25 lbs of that is live sand. I transferred a few cupfuls of live sand from my 29gal biocube that about 1 year running.

I placed 4 raw shrimp in the tank two weeks ago. They decays completely. My ammonia and nitrite levels when down to 0. My Nitrate levels are about 10. My LFS told me to add a couple more shrimp to see if I would get an ammonia spike. I added them on this past Saturday. My ammonia levels were are .30 the day after I added the additional shrimp. My Nitrite levels were about .25 also. My Nitrate levels went up to about 15 or 20 (hard to tell). Each day since the ammonia and Nitrite levels dropped. Yesterday they were at .25 (ammonia and nitrite). Today they are both at 0, with my Nitrate at 10. The additional shrimp are still decaying in my tank.

Since my levels are at 0 (except for Nitrate), do you think my tank has cycled? What can I do to make sure, and should I now remove the decaying shrimp?

FYI - I have 2 small oc clowns, 1 firetail, and 2 cleaner shrimp, and 1 small zoa frag in my 29 gal that I will be transferring over. I won't add any more livestock to the new tank for a week or so after I transfer these guys in.

Your thoughts are appreciated.

John

i think you are about done, but i would like to see the nitrates at 0 as well. how deep in 80lbs of sand in a 120 ?? i would recommend at least 4" in the display, this would also help to lower the nitrates to 0.
i would go ahead and yank that shrimp out.

i would add 1 fish from the other tank per week or so to allow the bacteria to keep up with the new waste from them.

Bobby,

Do you feel the Nitrates will drop naturally by the good bacteria digesting them in the tank or will only water change reduce the Nitrates?

Forgot to answer your question...My sand bed is between 3 - 5 inches.

usually WCs do not do very much for nitrates. it is possible that they will go down more, but not as likely if you start adding anything before they are at 0. i would wait a few days and test again. if they go down to 0, great, add 1 fish. wait a week or so, add another and so on. if they do not drop to 0 after a few days then post here and we can figure out why they are not dropping below where they are when you test in a few days.

DSB ... i would give it a week of so and test again ... it will likely go down more.

^^What he said.^^

You could drop a couple flakes of food in the tank every few days just to make sure the bacteria are being fed.

please tell me you bought a kg of shrimp to eat as well? :up:

cycle, wow, you really kick started your tank yeah, how many shrimp you use...lol

these guys are on the right track, but at the end of the day dont worry about trying to keep the bacteria alive,it will regulate itself regardless- just make sure its non toxic & reading 0's across the board before you add your edditions. this isn't your first BBQ though, how come your asking about cycles again bud? :huh:

Just being carefull I guess!

John,

The reason your Nitrates are up a bit is because a DSB, activated with aerobic bacteria from LS, is not necessarily activated with anaerobic bacteria in sufficient numbers to convert Nitrates to Nitrogen gas. That action happens in the deepest layers of the DSB. Two things need to happen BEFORE any conversion takes place. First anaerobic bacteria populations must multiply to sufficient numbers to convert the available Nitrate. Second the Nitrate available has to reach the deep layers of the DSB. Natural water circulation happens in the upper layers of the sand bed assisted by your sand stirrers. Since there is no natural water circulation in the lower reaches of the DSB the Nitrate laden water has to be transported there by another means. Below is pictured my 75 gal reef as it was being set up in 2002.

http://www.theculturedreef.com/75gal-6-18-02.jpg

It's easy to see the 5" DSB has two layers. The deepest is 4" of Aragonite sand and the upper layer is 1" of LS. This initial "inoculation" of LS is just the beginning. If that is all you add to your DSB it will be awhile before it can convert all the Nitrate produced as you add critters. An essential addition, one that many reefers new and old neglect, is LS bed activators. The most important of which is "spaghetti" worms.

http://www.theculturedreef.com/MedusaWorm-2.jpg

Spaghetti worms can be gotten on-line or from a reefer friend's established aquarium that has them. In the above picture it's plain to see the worm has tunneled into the sand bed. When they move through their tunnels they push water ahead of them, pulling water in from behind. It's this water movement that takes water to the deep layers of the DSB where anaerobic bacteria perform their magic converting Nitrate to Nitrogen gas.

http://www.theculturedreef.com/75gal-1-23-04%20(Changed).jpg

This picture shows the same aquarium about two years after setting it up. The DSB is healthy, functioning properly keeping the Nitrate below 10 ppm and usually 0 ppm. It's beneficial for some critters, like clams, to have a small amount of Nitrate in the aquarium. Nitrogen gas can be seen in the sand bed on the right below the Fungia coral.

I hope this helped clear up the reason for the Nitrate reading you are experiencing.

Dick

Great explanation Dick!

You should be in business my old friend, :huh: umm yea! lol