Controlled Plenum Wasting

Perhaps the author was thinking about potential clog issues within his draw system. I have not read through the entire thread to see if he gave his reasoning. Screen size would be dependent on substrate size. Substrate size will control what you are removing in the end. I suppose one needs to ask themself what are they looking to remove in the end? You want your substrate to be small enough to get a good anaerobic area going, but not be so small that you end up with clumping and a whole lot of melting. One more tidbit for you to think about....aerobic areas/water making their way into once anaerobic areas after a draw.

 

I have an inch of coral gravel covered by a screen that is the anaerobic zone. I have a 3 - 4" DSB on top of the screen with tons of sand stirrers and couple of sand tailing/burying fish. The screen, nylon screen door material, keeps the critters from disturbing the anaerobic zone.

So far, after two years, lots of nitrogen bubbles.

 

Craig - what I meant was, when the draw from the plenum space is taking place....the water present in the aerobic zone will be pulled into the anaerobic zone. How is that going to effect the anaerobic bacteria? Will it effect them? Would the tank experience a "mini cycle"?

Also, Craig, the bubbles you are seeing could be a mix between the nitrate conversion and algae respiration. Remember, you probably have small algae present in the bed, and will see some bubbles from them.

 

Nikki,

Good point.  I know you know more than most that the Nitrogen cycle is a LOT more complex than most people believe.  Since tank water is typically supersaturated with Oxygen, this drawing process is sure to kill all of the Obligate anaerobes.  Big deal.  Dr. Shimek told people that only Obligate anaerobic bacteria can denitrify but that just isn't true. The facultative anaerobes can handle Oxygen and can process Nitrogenous compounds as well as the Obligates.

This is an advantage in another way.....those Obligates are bad to the bone and like to curse, spit, and say dirty things.  Oops, I mean they produce Sulphide Zones, Ammonium, and other nasty substances.  In other words, I don't really care if they die.

 

Even if they did die; a healthy bed would more than compensate with new bacteria in a short period of time.

phil

 

Facultative anaerobes to the rescue!

 

Good point about the facultative anaerobes!! IMHO, a healthy sandbed will regenerate the lost anaerobes very quickly and I don't think that there will be any "mini-cycle" because you are not removing all of anything.

One of the questions in this thread was about removing 2 pints of fluid a day. Over a months period that is less than 8 gallons of water removed, and hopefully, replaced. In a tank that is 45g that is a little more than 20% water change per month. If it works its definitely easier on the back. ;D

I am not sure I get the pic posted by one of the authors at reefcentral.com (thanks for finding that, canon2222). That plenum looks like it is almost a closed system. It is my understanding that a plenum needs water flow in between the sandbed supports. I assume there are holes drilled but as the original author of the CPW article (posted at:

http://www.coralforum.com/ftopic1521.html&highlight=

)

clearly says that there should not be a lot of holes drilled. This makes sense to me because you then really would have to pull a lot of water through. I don't think that that was the intent here. IMO, the intent was to "drain" (slowly) a small amount of the nasties out of the plenum area, hence leaving some of the "nasties" and other good stuff to continue the cycle.

Correct me if I am wrong Oh Masters of the Reef, for I am but your humble newbie reefer and am easily mislead...

Actually, I'm glad I started this thread it has been very educational and you people have a vast range of knowledge to help me expand my horizons.

Drew

 

You are quite right Phil.  They will repopulate quickly.  Do some Googling on the lifecycles of bacteria and you will be shocked.  Some of those puppies are born, eat, reproduce, and die in a matter of hours.

I do want to point out that if you want to go with a system like this, you shouldn't feel the need to copy the authors methodology.  The author is merely trying to solve a biological problem by modifying a plenum physically and changing the typical husbandry of a plenum.  Like I said before, IMO this idea has merit but does it have to be done the same way as the author?  Most certainly not.  Decide what you want and find a way to get there.

I know someone on another board who intends to build a plenum with a drain and he intends to drain more water every couple of months as opposed to every day like the author does.  If you haven't figured it out by now, I am comptemplating something similar but I intend to have separate compartments and separate drains and I think I will drain one compartment monthly.  

I'm not worried about any flooding problems.  There are lots of physical ways to overcome flooding problems.  For instance....do drains always have to be at the bottom?

I have my reasons for wanting my system a certain way, the author has his/her reason, and my friend on another board has his reason.  Here are some thinking points...(and by thinking points I mean things to think about.  The author was attacked on another board by people who refused to think).

What is the Nitrogen cycle?
What does a DSB do?
What does a plenum do?
How do they differ?  
Is this difference useful?
Why would one want to drain the water under a plenum?
Are there disadvantages of draining the water?
If there are disadvantages, how do I solve that?
If I thought the advantages outweighed the disadvantages, what would be the best way to move forward?

Those are a few of the biological questions.  I'm gonna make it a little harder and throw out a few "big picture" questions and maybe they should be answered first.
 
What are you trying to accomplish?  I.e. What are your goals?
If there are difficulties associated with your goal, can they be overcome?
How?

(BTW....write those questions down....they will serve you well in your life and not just in reefing).

Ya know....thinkin' out loud can be cool too.  You're not gonna get attacked on 3R like this author was on another board...It never hurts to just throw spaghetti against the wall and see what sticks.

 

LOL, Curt - you had to bring up the nitrogen cycle. Just to make a comment about the nitrogen cycle....there is so much more to it than ammonia to nitrite to nitrate to gas....there are so many pathways and processes that occur. The "nitrogen cycle" is just one branch that can happen. There are many other off shoots and byproducts .... more than you could imagine. I can use the Monoco system as an example...the nitrate to ammonium - that is just one wrench in the "end" of the cycle.

Curt and I have discussed his modified plenum approach (with the compartmentalizing of the space for draws), as well as the other modified plenum design he mentioned. I think both will be cool, and I can't wait to see them in action.

Now, if the darn probes to put in there weren't so expensive...we could have some cool data, too.

 

Thanks inwall, may you and your reef have good karma. It's hard enough to keep our animals alive and healthy without being attacked by another person because he/she doesn't think that your idea will work!
Deep sand beds and or plenum's are far to complex to fully understand. There's biological and chemical changes going on that we don't fully understand how and why. But isn't this learning process one of the reasons we keep reef tanks or general aquariums in the first place?
You brought up so many good questions, (yes I did write them down ;D) sometimes we do forget to ask ourselves on what we are trying to accomplish! Much appreciated.
We try so hard to keep the water clean, we feed our animals a balanced diet, we try to give them the best light; we try to do everything thing just right, why not try to keep the dsb healthy? It can't hurt, right? I had a friend to keep his dsb for 7 to 8 years without it crashing because he vacuumed a different part of it every month. He believed it did get polluted and had to be cleaned out every so often. The question on my mind is not why it should be done because it needs to be, but how is it to be done. Many possibilities, we as fellow hobbyist together will find the answers to the questions that are being ask.
We have to explore what is best for our animals that we keep. We are responsible for their health and happiness. The esthetic's of our mini reefs should come after the care of the animals. Of course we should do both at the planning stage!


phil

P.S. Thanks 3Reef! This is the first forum where I feel like I'm part of the community. Keep up the good work! ;D