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Nitrogen fixing

Discussion in 'Expert Info' started by Wet Paycheck, Apr 13, 2021.

  1. Wet Paycheck

    Wet Paycheck Amphipod

    I’m supposing that the nitrogen fixing bacteria in the sand bed are the same as in the live rock. Can anyone confirm?
  2. jda123

    jda123 Tuna M.A.S.C Club Member

    There can be many different kinds/strains of bacteria, but they are all anxic, use the O in the no3 and covert it into nitrogen gas.

    There is some nuance that you must understand... and I will try and keep this short:

    They work best in concert with different critters creating pathways in each medium and the rock being stable if the sand gets disturbed, and vice versa, but one can work without the other. Sand has more ability to lower no3 than rock does - I use about 3 inches works great for denitrification and I don't see the need to use 6 inches which was popular many decades ago. Man made rock does not act like aragonite and is mostly more like a decoration, so treat it like a sunken pirate ship or a skull.

    If using dead or dry rock, it can take a few years before that rock can house a stable and effective anoxic bacteria population since the bound terrestrial phosphate and organic gunk creates a bad environment down into the pores that takes years to work out from the surface going inward. A new sandbed can be decent in a few months and really good in 9 months. The sand does need vacuumed over the years to remove detritus which, while benign/void of any nitrogen or phosphorous, can gum up the works and not allow the processes to work well - I vacuum out mine about every 4 years but only do 20-25% at a time and wait a few months in between.

    The aragonite sand and rock will also bind phosphate - it is just what it does in Chemistry 101 style. It can bind a lot and hide a husbandry problem with lack of export (fuge, skimming, etc.). Eventually it will fill up and the phosphate level will rise significantly in the tank. People used to call sand beds "time bombs" because of this, but the sand was not the problem, the lack of understanding and poor maintenance from the idiot keeper was the issue... along with message board parroters who latched on to the term time bomb and had no idea what they were saying. You need to watch your P level and still export so that the sand is a buffer and not a reservoir. I use chaeto, heavy skimming to keep my P about 1-3 ppb and I have no worries about it getting to growth limiting levels since the sand will release some if it gets too low (great buffer).

    Both sand and rock can be used indefinitely and while they can make routine maintenance next to nothing, they still take some work in the long term. Make sense?
    kchristensen8064 likes this.
  3. Wet Paycheck

    Wet Paycheck Amphipod

    Thank you very much for your reply. Now the problem of how to add more sand underwater! Lol
  4. Wet Paycheck

    Wet Paycheck Amphipod

    Also, I had no idea they banned real live rock! What else have they banned since I’ve been gone? Yellow tangs??
  5. SynDen

    SynDen Kraken Staff Member M.A.S.C Club Member M.A.S.C. B.O.D. M.A.S.C President M.A.S.C Webmaster

    You can use a funnel and a long length of pvc pipe to deposit the sand on the bottom. After you rinse the sand, put it back in the bag. Then submerge the bag, sink it to the sand bed, and then slowly turn it over and dump the sand out

    Ya quite a while back. Yellow tangs havent been banned per say but any exports out of Hawaii and a few other areas are banned now, so prices on yellow tangs have gone up quite a bit
  6. Wet Paycheck

    Wet Paycheck Amphipod

    Wow! I was kidding but this is all blowing my mind. I should have never decided to get back in. Seems like this hobby is dying out. Pretty soon all we will be able to own are clowns and Ora coral...
  7. jda123

    jda123 Tuna M.A.S.C Club Member

    Put 10-15 pounds of sand in a 5 gallon bucket and put your hose in the bottom of the bucket and move it all around until the water runs clear. Then you can use a funnel or 2" PVC to get it to the bottom. If you don't get lazy rinsing, this should not cloud up too much. Don't add more than 1/2 or 3/4 of an inch at a time since the critter and bacteria will need new time to move the right area and don't want to be buried alive.
  8. jda123

    jda123 Tuna M.A.S.C Club Member

    You can still get ocean live rock. There is cultured out of both the Atlantic and the Pacific. Both is well worth the money by the time that fight dinos, cyano and two years of inconsistent tank issues. Even a starter pack out of the Gulf of 20-40 pounds can seed the rest and speed it up a bit.
  9. Andrew_bram

    Andrew_bram Kraken M.A.S.C Club Member

    I recently got rock from kp aquatics was actually pretty nice rock. They claim no aptasia on their rock because it come from a different area.

    Sent from my SM-N986U using Tapatalk
  10. jda123

    jda123 Tuna M.A.S.C Club Member

    Trying for pest free live rock is a fools errand, but unfortunately too many people bought into the BS when dry/dead rock was advertised. Unless you are going to run a full-scale coral QT system with a few different levels, you are going to get pests, so just have a plan for them. The people who fought a few years of dinos, hair algae, etc now have aiptasia too. There are aiptasia eaters in the Keys, which is why that rock might be Aiptasia free, but it can come in on the first frag plug that you get.

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