DIY biofilter

[koikeepr]

yes, that works perfectly. Much easier to have to clean out one barrel more often than two.

Are you adding in an overflow emergency pipe, Shroeder? This would be a pipe at the higher point of the barrel above your main return pipe (water out pipe in your photo). In case the water line hits the overflow pipe, your water would be directed back into your pond by-passing your barrels.

 

[nc0gnet0]

An overflow pipe would be nice, but I caution its incorrect use. It would be nice to have should you decide to place a ball valve between barrel one and barrel two. This way you could shut off the flow to barrel two and bypass it for when you need to service it (this should not be often at all, however).

It's continual use however might deflect more water than you care too from being cycled into the second barrel. I can't say exactly how much because of the many variables at play here. I see that you have changed your design from a 1" pipe to a 2" pipe. This will help but only address's one of the variables I brought up earlier in your bottom fed second barrel.


Let me try a different approach to explain what is happening (and did happen in your original design).

Have you ever noticed when buying a pump that flow rates are listed at different head heights? Did you notice that as the head height increases, flow rate decreases? Why is this?

As water fills the pipe and is directed uphill, the wieght (mass) of the water in the pipe increases. The higher up the water has to travel, the more wieght the water has ( due to an increase in volume). Additionally, not only the vertical distance the water has to travel effects the weight, but the size of the pipe as well. For instance, if you take a small pond pump of say 2000 GPH and feed it through a 2" pipe a distance of 8 feet up a 45 degree slope into a waterfall basin, you will probably get a pretty decent flow ( I am guessing around 1400 GPH depending on the pump). Now if you take that same pump and feed it into a 20 inch pipe up the same distance, you probably won't get much flow at all as the pump cannot overcome the weight of the water and its resulting backpressure.

Now, why is this all relevant to you filter design? Well, when you bottom feed a barrel and force the water up, your effectively pushig the water through a 20" pipe (the barrel). Now all this is fine and good on your first barrel, but your doing it twice. So your first barrell fills and then begins to fill the second barrel. As the weight of the water accumulates in the second barrel causing backpressure, your going to reach a point where it is easier for the water to simply overfill and overflow in the first barrel rather than to continue to fill the second (in theory). Now in all likelyhood, the second barrel will fill and work, but your going to have x amount of overflow in the first barrel as well.

Seeing how we would like to eliminate this, why not seal the top of the first barrel, or better yet, top feed the second barrel? Why are you so set on bottom feeding the second barrel????

 

[newday3000]

another good reason to exit a barrel at the bottm is you're using gravity and weight of the water above the exit hole to increase the pressure and flow out of the barrel. When exiting a barrel at the top you are not getting any assistance from gravity or weight of the water. This makes a big difference in flow rate considering the barrel is 3 feet tall.

I'm also doing a 2 x 55 drum filter and I plan on exiting the bottom of each barrel for the reason above. I have a simple PVC pipe that splits the output of my pump to feed each barrel (also has check valve inline to ensure both drums don't gravity feed back into the pond if the power goes out, (3rd outlet is to feed my water fall)

 

[nc0gnet0]

another good reason to exit a barrel at the bottm is you're using gravity and weight of the water above the exit hole to increase the pressure and flow out of the barrel. When exiting a barrel at the top you are not getting any assistance from gravity or weight of the water. This makes a big difference in flow rate considering the barrel is 3 feet tall.

While this statement is entirely true, this design too has it's compromises. Mechanical filtration is best done from the bottom up, this helps the larger debris to settle in the bottom and reduce clogging of the filter media. This is why the bottom up design in a single barrel system works so well, you can flush the larger debris. if you top feed the first stage of filtration you going to find yourself replacing/cleaning the filter media much more often.

As per flow rate, your never going to get more flow out of the barrel then you put in, unless your sit there with a ball valve and close the valve and allow it to fill then open it to let it drain, over and over again.

Biological filtration is better from the top down, as you will have a larger concentration of good bacteria this way (kept wet but not submerged).

This said, in designing a pond filter (IMHO) more attention needs to be payed to good mechanical filtration over that of biological. Nitrosonomas and nitrobacter are going to populate every surface in your pond. The liner, the rocks, the plants, the soda can your neighbors child threw in your pond, etc etc. It will even populate the surface of your filter pads that your using for mechanical filtration. Thats not to say that bio-media is not important in your filter, it effectively increases surface are of your total pond and thus increases the amount of fish you can have. But, what I am saying, is that bio-filtration happens naturally. However, mechanical filtration does not.

 

[newday3000]

since I'm trying to move the drums about 15-20 feet from the pond I pickup a lot of effective head presussure from the tubing and height difference from pond to drums.

I want to get as much gravity working for me as I can to get water back into the pond on the return.

I like the idea of being able to add/remove/clean media from the top of the barrel. But since I have 2 barrels running independantly I may choose to dedicate one to Bio and one to mechanical. I have not decided on the final design yet.

I also wonder that everyone targets X turn over of the pond water per hour when they pick the pump size but given the poor design of the filter or drums and return rate due to gravity feed returns that it's not even close to the 1 or half pond volume turn over rate per hour.

When it comes to mechanical versus biological. I have to think Bio is more important as stuff breaks down it creates ammonia which kills fish. Mechanical just collects large particels but they still break down and create ammonia no matter where they are in the pond or collected nicely in the filter.

I suspect the DIY barrel filters are so effective due to the Bio advantage and not the pure mechanical aspect of the filter.

Bio filter's are many times the surface area of the pond liner, rocks itself. The key to the bio filter is water flow. the sides of the pond simple doesn't get enough water (fresh oxygen) to make the surface of the pond a very effective bio filter.

 

[nc0gnet0]

When it comes to mechanical versus biological. I have to think Bio is more important as stuff breaks down it creates ammonia which kills fish.

Well Bio IS more important that mechanical. But, bio happens naturally and mechanical does not. If you go with a bottom up design with the mechanical filtration, alot of the large debris can be flushed out via a bottom drain before it completely decomposes and produces ammonia.

Mechanical just collects large particels but they still break down and create ammonia no matter where they are in the pond or collected nicely in the filter.

This is not true. Almost all the media used in these skippy designs not only perform mechanical filtration but do double duty and provide and excellent breeding ground for good bacteria. For instance Koiguys design using scrubbie pads.......

 

[koikeepr]

my point of an emergency overflow is not one that will affect the daily use of the barrel in any way. It is exactly as I state: an emergency. Should either of the water levels get too high on the barrels, it would flow out safely as a bypass. This should theoretically, never have to happen. BUT, it's in place for that rainy day just in case. It would not affect any normal flow or function of a barrel. Just an extra higher hole for a just-in-case.

 

[Schroeder1959]

I'm also doing a 2 x 55 drum filter and I plan on exiting the bottom of each barrel for the reason above. I have a simple PVC pipe that splits the output of my pump to feed each barrel (also has check valve inline to ensure both drums don't gravity feed back into the pond if the power goes out, (3rd outlet is to feed my water fall)
QUOTE]

I have not yet started to build my 2 barrel system. I finally got my old system out yesterday, and today I test fitted my two barrels just to make sure they in fact to fit, and thank my lucky stars, they fit. Could you please give me a drawing of how you plan to connect your 2 barrel system? I am not sure I understand your photo and how it installs to your system. I am also planning on having a bottom drain in each of my barrels. I also thought about having two 2" outlets going back to my pond to make sure there isn't any overflow.

I agree, mechanical filtration can also do a lot of biological filtration. I have 4 levels of mechanical filtration in my skimmer before the water even gets to my pump which helps a lot. It also helps keeping my barrel system clean.

So if you could please write up some instructions of your system, I would really appreciate it. I am going to build my system in my heated garage this winter, and then will lift the entire system in place with some help from a few of my friends. Not too heavy, but bulky.

Thank you!!

 

[nc0gnet0]

my point of an emergency overflow is not one that will affect the daily use of the barrel in any way. It is exactly as I state: an emergency.

I know this, however, considering Shroeder's design, I suspect he may be in constant state of overflow. I do realise however this was not your intent in suggesting the EO

 

[newday3000]

good old powerpoint... threw this together of what I'm working on over the winter. This thread shows what I've done so far and couple tests I ran to see how the flow went. https://www.gardenpondforum.com/my-attempt-55g-filter-t4481.html

I was not happy with the flow rate which is why I want a top fed solution to use gravity and head to get more flow out the 2" return.

 

[nc0gnet0]

have you tested this design out or is it still in the planning/construction stages?

You say your barrels are 20 feet from your pond, may I ask how much above the pump are they elevated? it looks like alot of work for one 2500 GPH pump but alot will have to do with head height. It would be interesting to be able to gauge your return flow rate but quite a pain.

I see your using three ball valves to control the flow rate to each resovoir. In your diagram you are aiming to have the barrel slated for mechanical filtration as the slowest flow rate. Are you pre-filtering this water so no debris cloggs the partially closed ball valve?

With the bio barrel slated for the highest flow rate, won't it in turn also recieve the highest amount of free floating debris? Will there be enough flow rate in the mechanical barrel to push the larger debris through the pipe?

 

[Schroeder1959]

Here is a drawing I made using Publisher. I think I have just about everything on this drawing. Let me know if you have any questions.

 

[Schroeder1959]

Just in case you can't open a .pdf file, here is an image of the same file...

 

[nc0gnet0]

Actually the question was directed at newday, but your design looks good now that you have the lid on. I would still top feed the second barrel, it would eliminate the need for an airstone (which would be optional anyways), But thats just me. if you like you could leave 1/3 of the bio media submerged and still top feed. Your lid will eliminate overflows and effectively make the first barrel a pressure filter.

 

[newday3000]

Definitely plan on a pre-filter. Have not started on that yet. My other pond has simple PVC capped with holes drilled in it and it work very well all summer. Will do something different on the new pond.

I've calculated 4' of effective head barrel plus hose length. I checked my spreadsheet measurements and hose is more like 12'. My pump can produce 1400 GPH at 4' head. a 2" hose and drain with head pressure can flow at 700 GPH (in theory). I tested the barrels using 1.5" hose (which can gravity drain at 350 GPH) and it overflowed so I went to 2" for the exit.

I was draining at the top of the barrel which has no head pressure assistance from gravity but a bottom exit should give me 3' of head pressure to get the flow rate up. I never got a chance to test the 2" exit from the bottom. My goal is to maximize my pump flow and get a maximum pond turn over I can.

I may decide to dedicate a pump for the water fall in the end if splitting the pump 3 ways reduces flow too much. I may also get a bigger pump to simplify the plumbing and just blast away to get the GPH I want to both drums and water fall.