Filtration - A thought

After doing a lot of research and googling and thinking I came to the following conclusion - What is our Filtration for ?

The filtration we use is to get rid of all the pollutants in the tank (stop the fish swimming in their own sewerage !!!!) ie. get rid of organic waste, dissolved and otherwise, ammonia, nitrite and nitrate. What we are trying to do is what nature does everyday in dams, lakes rivers, seas, oceans.. The difference is ours is a very small closed system, normally with a huge bio load compared to nature.

What would be the ultimate filtration system :- one that would provide perfect water all the time, never need servicing and would only need topping up. ( No water changes, and as little maintenance as possible. )

So we need to look at how nature does it and then try and replicate that system.First nature has MUCH lower bio loads. (That is one thing we will never be able to do as hobbyists. (1 neon tetra in a 2m tank - I DONT THINK SO)

Ok so bio load aside, How do we make the ULTIMATE filter or filtration system.Lets look at nature and try to duplicate that, taking into account all the present filters used by all hobbyists, freshwater,brackish, marine and coldwater. While we are on topic, there are amazing technologies being used in wasetwater treatment plants all over the world - so factor some of that in as well. So lets look at a simple wastewater treatment plant as it is a microcosm of what nature does.

Water enters the plant - The big bits of organic waste are MECHANICALLY FILTERED out by screens, and the heavy stones and grit are removed.

The water then goes to a settling tank. Here the remaining solids settle out and are sent to a digestor. The fats, oil and grease floats to the top and is skimmed off and also sent to the digestor.

The relatively clean water then flows to an AERATION, biological treatment dam or tank. Here, most of the the remaining solids are eaten by the aerobic (needing oxygen) bacteria, which require the oxygen supplied by aerators to multiply.

This liquid mixture, composed of solids with micro-organisms and water, is sent to the CLARIFIER. Here the solids settle to the bottom where some of the material is sent to the digestor, and some is recirculated to replenish the population of micro-organisms in the aeration dam to treat incoming wastewater.

After clarification the water is disinfected to kill harmful micro-organisms before being released back into rivers etc.The disinfectant is normally chlorine.

In the DIGESTOR the solids, fats, oil and grease, is converted by anaerobic bacteria (not needing oxygen), into methane, water and a solid called biosolid. This biosolid is then pressed dried and sold as fertilizer.

So what we have is :
Mechanical Filtration, Aeration, Digestion (both aerobic and anaerobic) and lastly clarification.

Lets apply these to build the ULTIMATE filter.

Water from the tank goes via an overflow into some kind of mechanical filter. This would be coarse sponge, then filter wool.

This water is then aerated by either a trickle tower or something like the Koi guys Bakki tower. This provides huge amounts of aeration, and at the same time the media the water is flowing over contains the aerobic bacteria.

The water is now mostly clean, the ammonia, nitrites and nitrates are mostly removed. The bakki tower with its high evenly spread flow rate and media seems to be the better way to go, as some nitrogenous gasses are lost to atmosphere and oxygen is plentiful due to the design.

This water then enters a tank (sump) that has a thick layer of fine sand (150mm) on the bottom, with a thinner layer of coarse sand (50mm) on top of it. This creates an anaerobic media for the bacteria which will remove the last of the ammonia and nitrates. (The marine guys call this a refugium)

Half of this sand bed can then be heavily planted with some of the more aggressive plants growing emersed. The plants will then take up any residual chemicals, metals, nitrates and ammonia if present. This is the Clarification stage.

The water leaving this tank can then go to a holding tank where it is heated and pumped back into the tank.

I have left out a lot of the details, which gives us a wide scope to research and make comments. !!!!!

I JUST have to now create the above in a design that is small enough to be used on a 450mm tank, but can be scaled up to huge ponds !!!

What does the forum think !!! Cmon guys and gals lets design an ULTIMATE filter that only needs to be cleaned out once a year with NO water changes.......

 

Interesting idea. I like your thought process.

I believe that the ultimate filtration on a tank would be a 1 to 1 sized sump. So if you have a 10 foot tank, you should back it up with a 10 foot sump. That way, you are in theory doubling up on the amount of water, thus reducing the bioload and leaving space for an incredible amount of bacteria surface available. Using a DSB like the marine guys do, and alot of ceramic rings and sponges and floss for the solids removal... I think that would be the ultimate filtration system for a tank.

Just make sure you stock for the top tank, and not the sump.

And if you so desire, you could add the biggest cannister filter you can find and connect it to the sump. No pipes going into the tank, all in and out of the sump.

 

There is a DIY you can do...

The idea was the as the water drained from the tank towards the sump, it flowed over a porous, flat surface. As the water flowed over it, 1 or 2 very high powered lights are meant to be shining onto it.

Therefore, algae will grow huge and thick there. As the water passes over this surface, the mass of algae eats up the nitrogenous wastes, filtering your water. It also means that there is likely to be less algae in your tank.

There's my thought.

 

A good idea but wouldn't this cause an unpleasant smell???

 

It's called an algae screen. And yes, it could cause a nasty smell, but you harvest the algae every now and again and if you keep malawis or tangs that are vegetarians, feed it to them...

 

This concept of an algae screen is similar to the marine refugium, right? Serves the same purpose, I think. But what about algae spores entering your display tank? Surely conditions in the water would be the same and if they grow on the screen they can grow anywhere else. Only difference is light levels. So you would have to try and find an algae type that does really well with high light and poorly under normal tank lights.

 

It's not a cure for algae, but it's one of the battles you can fight.

 

I think It would encourage algae growth in a specific area and the algae would not be competing with the plants in the main display tank. I know of a couple of people using this method very successfully. And they actually have very little algae in their tanks...

There isn't really a need to seed the screen, it will seed itself after a few days... Hmmm... Something else to look at...

 

Hi I would say the filter has nothing to do with the tank size but with the waste load. A empty tank doesn't need a filter!
But I also think that in a relativly small filter with a large surface and a lot of O2 and time a lot of waste can be processed.
If one creates enough surface in a system (3D background, sponge, bioballs etc)4 enough Bacteria to settle and gives these bacteria the right condition (O2, flow rate) you can process more waste than in a normal stocked tank accumulates.
The proof of that is if you have a tank with hardly any waste(low fish stock little food) you can see bacteria cultures deminishing on a sponge filter due to lack of food.
So i think the filter size is often over vallued. One of the great short comings of canister filter is in my oppinion not the size but that the water passes thru much to fast, because most people judge a filter by its pump capacity, the more the better.

 

Which is why I now run 2 cannisters to give me a combined flow rate of what I need for my tank size, yet individually water passes over the media fairly slowly.

 

But on the other hand, it's not just fish waste that causes pollutants in a tank. In a fully planted tank, dead and decaying plants also add to the waste load. Also bogwood and driftwood begin to decay as well. Whether we like it or not, a tank with no fish at all, could also have a waste load. But let's be honest, you have a massive tank with hardly any fish? I highly doubt it.

Me personally, my tank would be very heavily planted.

 

Nope. Algae turf scrubber is totally different. Vertical piece of glass or netting with water being pumped to the top and the water trickling down. Lights on either side for growth.

The idea is that the scrubber gets the algae going and grows on the media rather than in the display tank. They run on a reverse light cycle, so probably get 14 -16 hours photo period rather than the 8-10 of the DT. With all the algal growth, should see reductions in N03 and P04. Not such a good idea when you have a heavily planted tank but great for a marine system where you want those to be params to be as close to 0 as possible.

Wonder if anybody has used Denitrator and Phosban reactors on a FW tank. Then you could get away with a smaller filter but would need regular siphoning

 

Zafgak - I think you are right - we need plants that grow emmersed as part of the final stage. Huge aeration - maybe sprayer bar onto filter media instead of having the media stuck in the water column.

You might want to play with the idea of using hydroton as part of your media filter - my convict tank now has a hydroton only grow trough, a pump with a sponge filter on in take pumps water via a spraybar like pipe into this 93x3x10 cm trough on a back shelf above the water line. I do need more light for the plants to grow well since this tank currently has not light - but ambient. But the over-populated tank is very health - water smells like wet sand no sent of fish or any decay ..

 

Guys the first post has been totally re-done, as I was just starting it when I hit the post button.. So please read the first post before commenting

Thanx

 

Ahhhhh okay - now some of the other posts make more sense

 

Good morning all
Not a space saving design i've seen on a show tank.
They hat a low planter attached to the tank and that filled with Hydro-culture balls(earated clay balls) in there the grew the small Papyrus grass under lots of light. The Papyrus was than harvested from time to time. I don't know at what rate nitrogen and other minerals where remooved but they said it made all the differents. It was a Arrowana show tank with 3 one meter fish besides some cat fish.
Another question, do we need as much filtering? The waste load in a AQ is normally limited, the amountas well as the kind of waste.
Please correct me but we only want or need to get out the N- compounds but would like to keep most other minerals for better plant growth?

 

Good point - the ultimate filter would take out all the minerals etc - so you would need ferts...

 

Gavin I have thought about this for quite sometime and I am very grateful that you have started this thread.

 

Me too. We are planning on building a 2.4m or 3.4m tank and I am busy designing the sump for this tank. Will be following this thread with great interrest

 

me 2...Hell Carping a 3.4 meter setup?!?!?! It will be a monster and you will definitely benefit from such a filter system as described above.