Controlled Plenum Wasting

If we continue to combine all these ideas we're going to have a very flexible sandbed concept that can be used in any number of differing situations. ;D

I'm thinking of using 3/8" pvc to construct a system within the support structure of the plenum that will be able to be flushed out in case of any blockage.The trick will be to figure out how to backflush the 3/8 drainage system without disturbing the sandbed and have the ability to suck or drain out the some of the fluid under the plenum. Maybe some sort of check valve configuration so that the fluid can only go in one direction....[glow=red,2,300]OUT[/glow] no matter if you are draining or flushing!!

[smiley=thinking2.gif]​

I feel that photoshop diagram itch coming on!!!

Keep on keepin' on gang...I love this stuff!!! 8)

Drew

 

I have a couple of ideas in my head. I'll more than likely use 1/2 inch pvc for the construction. Don't know about the hole size or how many just yet not to mention how far to put the holes. You want them small and spaced regularly apart to draw in the waste but not to big to act like a huge siphon. The thought of a back flush still has me thinking. Instead of one drainage pipe handling both removal and back flushing, maybe two pipes would work better. One to pull out the sludge and the other to back flush the bed with fresh tank water. Think of this way, on the highway leaving town, you have two lanes heading north (waste) and two lanes heading south (fresh water) to back flush the dsb. You would have to use a couple of check valves and maybe a gate valve or two, but it could work i guess.

phil

 

Phil, it seems like you are thinking along the same lines that I am. I just found a good local source for 3/8" acrylic tubing that will sell me pieces.

What I'm thinking is that the plenum I already have, which is based on 3/4" pvc, eggcrate, and nylon screening, will have the secondary system in it made up of about six 3/8" acrylic tubing pieces of varying lengths fanned out from a central point at the back of the aquarium, then group the ends together into one upright going to the top of the tank. Each 3/8" piece will be drilled, after that I am not clear yet, but you would be able to syphon a slow trickle out of that secondary system.

Your highway analogy is a good way to see it!!

 

Thanks, I'm glad that I'm not the only one thinking about this crazy thing. The more I think about, the more I'm convinced it will work. If your using the one pipe method than you'll just end out putting more junk into the bottom of the tank bed.

I'm thinking that I will forgo the eggcrate and just use the sceen mesh. I've been reading a lot on dsb's lately, to my understanding dsb's have an irregular pattern to them. We can try to keep it even but it does shift. The screen will be there to keep animals from being sucked down.

Hey dx7fd2, have you thought of sand size yet? Some including the original author said that you should go with cc. While others say sugar size. Personally, I may go for something in between, haven't decided yet. Another thing to consider is the depth. I read someplace that most of the denitrification takes place in the first couple of inches. If this is correct then anything above two to three inches is wasted space. Right now i'm thinking maybe a two, two and a half inch bed.



phil

 

[quote author=cannon2222 link=board=Sand;num=1087396461;start=30#39 date=06/24/04 at 13:13:39] 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.[/quote]

Phil...your friend is breaking all of the rules by thinking for himself/herself. This must be stopped!!!

Matt, ya got yourself a couple of rebels here who are going to have to be monitored for original thinking. You aren't going to allow that to continue are you??? (obviously said tongue in cheek).

 

Can't...stop...original...thinking.... Resistance is futile. ;D


phil

 

You guys are real cards!

 

You shall be assimilated.

 

hehe.. Man this is great to see. People actually throwing ideas around without negative recourse!You guys are great! 8)

I've metioned my concerns over the physical setup of such a modified plenum.. now I want to go back to the ~reason~ you guys want to do this...

Inwall mentioned ammonia raising on the Jaubert setup. Is this the prime motivator? Are we going off one example here? Now I am about as far from a omniscient person as you can find - I was a Communications major in college for crying out loud and I have my vices, but I have to say, as a guy that's read a bit about plenums and things from people with plenums, this is the first I've heard of it.

I've heard the one about the hair algae.. and the one about the hydrogen sulfide gas bomb, but ammonia off the charts, not a thing. Most of these plenum stories come second hand like tumbleweeds too, which makes it kinda frustrating when you really are digging for dirt. Maybe I just missed this one.

Anyway, lets give this some thought, ammonia is one thing most of us don't worry about most of the time even though it's pretty lethal. Once we get through the cycle, it seems to go away and out of our mind. Everyone seems to say surface area breeds bacteria which convert the ammonia to less lethal nitrites, etc..

So my disconnect seems to happen here. Again, I am not the sharpest tool in the shed, so pardon my ignorance. ;D If there are more examples of the ammonia thing with plenums, please let me know where I can read about them. Or dumb this point down so I can understand where you are coming from. Seriously!

 

Ironically I just happened to pick up Bob Goeman's Sand Secrets. What timing with all this plenum talk. Bob picked up the plenum baton and has been running with it for a long time so I'd like to share a some of it here to hopefully add to the discussion and give some plenum background to those that don't know. I don't this to be taken as gospel or that I am selling plenums. I'll get to my spin at the end.

Anyway, Bob looks at DSBs and the oceans sandbeds as being efficient in their biological processes for only a couple millimeters. Beyond that the less effecient anaerobic proccesses kick in. He sees all sandbeds as chemical sinks and the 'diffusion of nutrients through their depth is a function of gravity and electrical charge' which is measure in millivolts (mV). 'The flow of unlike charges are from positive to negative.' He says that the bulkwater above the sand is a soup of charged particles, mostly positive. The surface of the sand is mostly negative and becomes increasingly negative with depth. His whole deal is that the plenum - an open space - provides a higher ORP than the sandbed above, although still slightly negative. 'It is this slightly higher condition that keeps the above sandbed mostly in an anoxic** condition. Thus, diffusion and the flux of nutrients are regulated by reduction-oxidation (redox). From there, energy and metabolism pathways of microbial populations take control.'

**Anoxic - Bob defines this as very low oxygen. Not devoid of oxygen. I can't remember where I read his explanation for this, but it's important to note.

He sees DSBs beyond the surface becoming a storage area for nutrients.

So with his plenum he feels he is really stretching out the effeciency of the sandbed and creating a more balanced system. He feels really strongly about this and sees it as a huge improvement over DSB and even nature the ocean floor. Now I wouldn't have said the later myself, but I understand his point I think.

Where he starts to sell me is with the sand itself. He advocates the bigger stuff, 2-4mm, because of fluid dynamics I believe and the fact that it won't get as compacted as the suger fine stuff. Proponents of DSBs don't like to siphon either as they worry about sucking up bugs and bacteria and stuff accumulates. And if you buy his thoughts on electrical charges, it should accumulate faster in a DSB. Bob siphons parts of his remote plenum from time to time.

After some tinkering around with Sam Gamble, he says the optimum sandbed for proper dissolved oxygen gradients/redox throughout the bed is 4 inches of the aragonite sand over a 1 - 1.5 inch plenum.

It's interesting to note that a lot of their tinkering came about after Sam (who was working for public aquarium in Key Largo) noticed reduced nutrient levels in all aquariums with common undergravel plates during a prolonged power outage during Hurricane Andrew.

So I say tinker away. I think it's great. A few short years ago, I was laughed at when I'd bring up plenums when the DSB fervor was strong. Funny how things go full circle. When I first go into salt in '91, wet/drys were a Godsend over canisters. Then a couple years later barebottom 'berlin' tanks were the rage. I would like to think that this hobby is evolving and people are becoming more accepting of methods that others use. It's a constant struggle to mimic mother nature, whatever works for you is what you should do.

I've had a small plenum in a 6 gallon plant tank of all things for years and have a salt nano hex now with 4 inches of local Northern California beach sand, nsw and diy rock. I'm all over the place. I've made huge mistakes and had some success. It's not the real thing, it's a glass box. I enjoy and observe it and
try to keep learning as I go. Husbandry is key though to me. Some sand setup won't save you if you blow off your chores.

If you guys want to drain a little bit of water from bottom of the tank, as I mentioned, it's not entirely clear to me yet as to why, but what the heck. I will continue to read whatever you care to share. I think it's cool. Sometimes the KISS principal is boring. It's hard to learn anything without experience or taking a risk sometimes, so I say keep hashing it out and give it a try. Maybe it will help us all out.

Matt