Is A Self-Contained System Possible?

[rojowe]

Hey Guys,
I'm looking to set-up yet another tank. I'm looking to do a 120, 180, or 210 gallon tank. I'm not exactly sure yet, whatever I can get a good deal on. I want to set it up as a freshwater oddball pred tank, possibly a ray tank, for the ray I know I will need at least the 180. I plan on having the tank drilled in the bottom with overflows. Obviously a sump, but in the sump I want to do 3 chambers. The first would be for filter floss and bio-balls or scrubies...then the second I want to do a refugium and the 3rd would be the return. I want to set up all my equipment in the sump so its only habitat in the tank. I don't know if I can eliminate water changes but I want to try and get close at least. If the refugium was decently planted could I at least drastically lower nitrate levels? I feel like it could work I'm just not sure totally. I want this to be an almost self contained if not fully self contained system.
What do you guys think? Any recommendations?
Rob

 

[fishbum]

Using a drip system would work better if you want to eliminate water changes.I doubt you could stuff enough plants into a sump to reduce nitrates that much,and even if you could,plants need fresh water too.

 

[gomezladdams]

With a large predator?No
If you want to get a start on understanding the science involved in creating a closed ecosystem in a tank,get a copy of Diana Walstads book "the planted tank"

 

[JK47]

One thing to keep in mind is that you need to do WC's not just to reduce nitrates but to replenish trace elements back into the system. If your sole pupose is to reduce WC's a drip system is our best best and least stress on your system. If you just want to tinker with plants and equipment then have a Google at "aquaponics". Why get nitrates at all from the nitrogen cycle when you can have plants consume ammonia and never convert them in the first place. It won't IMO happen in the small space provided in your sump but do some research and you'll see what I am refering to.

 

[Toby_H]

Yes you can keep nitrates down to a trace level using a planted refugium...


The quantity of plants would depend on the type of plant and quantity/size of fish. If you were to do a pair of Rays in a 180+ Gal, I suspect you could realistically do this.. If you want your display tank densely stock I doubt it could be practically done...


When using a refugium, I do not think you would want/need/benefit from Bio Media. I feel the space that the bio media would be taking up would be more efficiently used as additional refugium space.


Bio Media simply hosts bacteria which converts ammonia into nitrate... plants serve the same person (removing ammonia nitrite) they just do so more efficiently as they also remove / do not produce nitrates... Thus, when using a refugium, I see no purpose in using sump space as a bio chamber...

 

[rojowe]

nc_nutcase
I get what your saying about bioballs and I've been thinking the same thing, i noticed since i started using them ive had nitrates and algae in my tank. never used bioballs before and never had algae. So I figured I might just eliminate them. Its good to hear that they wont really be needed with a fuge. I'm thinking 55 gallon tank under the 180 so probably 30-40 gallons actually being used in the fuge without the risk of overflow...
I dont plan on stocking up whatever tank i get full...i usually like to only keep a few fish per tank.

 

[the_deeb]

This is something I'd really like to try at some point as well, but IMO you're not going to be able to accomplish this with the typically sized sump on large pred tank - the fish just produce too much waste. I would think even a single pair of rays in a 180 would be too much as they grow.

Diana Walstad and Tom Barr have promoted heavily planted, 0 water change setups but a key component is a relatively light stocking load. You're talking schools of tetras in a 180.

For something like this to work with a pred tank you'd want to link your tank up to a LARGE planted refugium (perhaps even bigger than the display tank itself) with predominantly emmersed plants (so CO2 is not limiting) and preferably outdoors or under a skylight (so you're not wasting loads of electricity providing sufficient light). People have been using these to filter ponds for a while. Look up "veggie filter" for more info.

I set up a small, ghetto version of something like this when I was in college as an aquaponics experiment - densely stocked 50g rubbermaid tub linked to a series of 3 more 50g tubs of latterite planted hydroponically with water lettuce, lillies and marsh grass. The planted portion of the setup was maintained in a greenhouse and there was no other filtrtration on the setup. I had 0 ammonia, 0 nitrite and <5ppm nitrates over the course of about 4 months that it was running. So it seemed to work beautifully, but the planted area was much greater than the display.

Another point to consider is that I was only measuring nitrates. While we typically use these as a measure of how "dirty" the water is, another important aspect of water changes is removing dissolved organic carbon (DOCs) and it's unlikely that plants will lower these and will in fact probably add more. That being said, it's also not clear how harmful DOCs are to the fish themselves. I would guess that, provided enough room in the filtration setup, heterotrophic bacteria may be able to break them down but am not sure about the optimal conditions.

It's a cool idea and might be feasible in the right setup but I think, In the long run, an auto water changer or drip system may just be easier for most of us.

 

[rojowe]

I guess im just going to try and reduce nitrates, instead of doing a water change once every week maybe be able to water change once every other week or after 2 weeks or something...its not so much about the ease of water changes IMO its more of less water changes...I realize i asked about self containment but thats just ideal, really im looking for easy care...
I'm also looking at just housing a single larger puffer

 

[brianp]

My recollection of plant biochemistry is that they get the environmental nitrogen that they require for amino acid synthesis primarily from NITRATE and smaller quantities from free ammonia. I am not aware that plants assimilate nitrite to any significant extent...but I could be wrong about this. What is clear is that plants have very active metabolic pathways for nitrate and nitrite reduction. In other words, they do exactly the reverse of what the biofilter bacteria have done to produce nitrite from ammonia and then nitrate from nitrite. In the first step, the plants reduce nitrate (NO3) to nitrite (NO2) and in the second step, reduce nitrite to ammonia (NH3). This ammonia is toxic to the plants, but is rapidly incorporated as the amino group in amino acids. These amino acids are then used to synthesize proteins by the plant. Therefore, I would think that the best possible system would be to use biomedia to efficiently facilitate the oxidative pathway from ammonia to nitrate in combination with plants which would then assimilate the nitrate into their growing tissues.