Is a biofilter supposed to be outside the pond?

[Meyer Jordan]

What makes one biofilter better than another?

Assuming that all equally convert the same amount of Ammonia, then I would think that ease of maintenance and possibly total footprint could be deciding factors.

 

[Koi4JT]

Hi, I have a 1300 gallon pond, and I am planning to build a DIY biofilter. As I am searching the net - it seems that in all the designs the filter is outside the pond. Is there a reason for this? My plan is [was] to make a submersible filter, but now I have my doubts. Can someone please be so kind as to tell me what is wrong with my logic?

What I plan is a tote box, sitting on the bottom, connected to my pump. Forgive my hand drawn diagram! I have a 2000g/h pump, and was planning to line the tote with filter sponges --> bioballs --> carbon.

The reason I have for making it submersible is to hide the setup, and not have an eyesore outside.

I would like any suggestions, please.

When I first built my pond, similar size to yours, I built my own above ground bio-filter. It worked great but was a weekly nightmare to clean. When I decided to expand my pond by 50%, the new pond area blocked where my bio-filter was located, so I did some research and chose to build a "bog", essentially another pond (60"W x 24"L x 48"D) filled with pea gravel. It works incredibly well, the ponds require no maintenance, and once every couple of years or so I backwash the bog. As far as i am concerned, the bog is the best way to go and I grow plants in the top so it looks quite natural.

 

[barryian]

Using rules of thumb can be dangerous because they usually have no basis in fact and may result in the "thumb" being in your eye or stuck up some other unmentionable location. They are entirely too vague. I am especially leery when the author can not even spell-

• 10 % pond volume in filteration (sic) volume

• 1/3 of total surface area of pond = surface area needed for fliteration (sic).

(From the Koiphen link).

And even though it is reasonable to assume that Matala knows what the SSA is of their pads, even they are vague in the use of terms like light. medium and heavy fish loads. These terms are subjective and open to individual interpretation.

Did notice that spelling also!

 

[Waterbug]

Carbon would be a mechanical filter element.I personally don't care for combo filters. Mechanical is a whole deal I won't get into here.

For bio above ground has been proven much more efficient, like 10x or more. The increased O2 makes bacteria happier and also above ground keeps the bacteria cleaner which means it can get to O2 and other chemicals in the water. These are also easier and cheaper to build than virtually all submerged filters and virtually never need to be cleaned. This also makes them steady at removing ammonia while a submerged will decrease in performance as it clogs. I think a case could be made for submerged bio filters not working at all. Keep in mind the entire pond, the pipes/hose, are a bio filter. Google "Trickle Tower" and "Shower filter" for more info. Most will be large, but they can be scaled to very small.

High fish load ponds need bio filters. Virtually all water gardens do not need any. Because of that it doesn't normally matter whether submerged or not. Lot's of people with submerged filters think the world of them, and give no credit to the bacteria on the pond walls or the algae which is doing virtually all bio filtering. For many people, especially in the high end, it seems like the water and fish are just an excuse for have large, complex, expensive filters. The filters ARE the hobby.

Rules of thumb on filter size can seem pretty silly the more you learn. A filter that's 10x more efficient certainly should be a factor seems to me. The amount of fish by weight certainly key too. Amount of food being fed also, and that's normally related to fish size. Feeding fish 12 times a day with an auto feeder vs a couple times on the weekend makes a difference. Using pond volume as a factor never made any sense to me, but yeah, see it a lot online. Same for pump size.

Bottom line is keeping a pond is a hobby so you should do what makes you happy. There's no right or wrong as long as you're having fun. Making submerged filters is a lot of fun...not sure why.I sure used to enjoy it.

 

[makuck]

I would ditto what Waterbug said.

My take on this is based on large aquariums which usually require intensive filtration I have managed to get away with no filter changes on medium-density tanks:

I always go with planted bottoms. Planted bottom tanks and ponds are great, plants are a great oxygenator and take up excess nutrients/excrement.

In my experience, with planted tanks: if you have just a ton of lava rock, polyester fill (like for blankets or pillows found at wall mart cheap), plastic scrubby pads you can just stack those things up and run water through them and good bacteria will grow like crazy, you will never ever have to replace any of it, if you have enough surface area. The surface area is key. More surface area means more oxygen. Even just pumping water up and dropping it down aerates it. The key is moving the water oxygenates it. Air bubblers are good. If you can make a small stream or waterfall all the more balancing that will be to the small pond. Air is an input but a really cheap one and can really help get the beneficial bacteria, plants & algae started, and it's essential for any fish, as important as the filter. Size trumps almost any problem with the filter. Overbuild it and force the water through as much of it as possible. I like to do tiers and drill holes so the water rains down through each level of filtration. A couple 5-gallon buckets filled with media would probably work. If you wanted to go all-out a 30-55G drum. The bigger your filter is the less algae growth and ammonia spikes etc there will be. Big surface area of biological action = good no matter how you cut it.

 

[makuck]

Carbon is pretty useless, it will just leech back contaminants into the water at a certain point. It's all about surface area, porous materials and stuff good bacteria can colonize.

 

[Meyer Jordan]

Carbon is pretty useless, it will just leech back contaminants into the water at a certain point. It's all about surface area, porous materials and stuff good bacteria can colonize.

Really?
Although it is true that certain Activated Charcoals (depending on manufacturing) may leach a small amount of Phosphorus, even this can be averted with simple pre-treatment. Even when saturated, AC does not leach any substances unless re-generation is applied

 

[Waterbug]

Stuff accumulates in the carbon, bacteria eat the stuff and release stuff back into the water. Carbon is good for specific things but as a general mechanical filter for ponds it's hard to see any benefit. Especially when cost is factored in.

 

[Meyer Jordan]

Stuff accumulates in any filter media or pad, "bacteria eat the stuff and release it back into the water"........Normal part of the aquatic Carbon cycle. I fail to see how this. relates to AC and toxins.
Activated Charcoal is not meant to be used as part of mechanical filtration but rather as a chemical filter much like zeolite.
The point is...AC will not release (leach) any captured toxins or pollutants back into the water column once saturated. It just becomes ineffective and either needs to be replaced or re-generated.

 

[Waterbug]

Yep. Which is why all submerged mechanical filtering isn't highly thought of in higher end ponds. In water gardens it's fine because it doesn't really matter if it works or not, the pond will be fine. Owners often imagine seeing a difference but actual testing has always shown it to have no effect in virtually all cases.

In serious filtering carbon is used at or very near the end of processing so the water is extremely clean going in. Dirty water just clogs the carbon and renders it worthless because the chemicals can't get near the carbon. For carbon to have any effect in a pond a very large amount would be needed and replaced every few hours. Not an economical process. High end ponds, water treatment plants, drinking water filtering companies, who take water clarity very seriously, use multi stage filters. Each stage is designed to remove smaller and smaller bits in the most efficient manner. Carbon, if used, is at or near the very end.

In the back yard trade carbon is just for fun. No real effect good or bad.

 

[Meyer Jordan]

Yep. Which is why all submerged mechanical filtering isn't highly thought of in higher end ponds. In water gardens it's fine because it doesn't really matter if it works or not, the pond will be fine. Owners often imagine seeing a difference but actual testing has always shown it to have no effect in virtually all cases.

In serious filtering carbon is used at or very near the end of processing so the water is extremely clean going in. Dirty water just clogs the carbon and renders it worthless because the chemicals can't get near the carbon. For carbon to have any effect in a pond a very large amount would be needed and replaced every few hours. Not an economical process. High end ponds, water treatment plants, drinking water filtering companies, who take water clarity very seriously, use multi stage filters. Each stage is designed to remove smaller and smaller bits in the most efficient manner. Carbon, if used, is at or near the very end.

In the back yard trade carbon is just for fun. No real effect good or bad.

Generally in agreement. The regular on-going use of AC in a pond is only a waste of money.
However, in the event of suspected contamination by pesticides, herbicides or other VOCs, then AC is absolutely indicated as it will quickly capture and reduce the levels of these compounds.

 

[Waterbug]

Carbon sure does work to remove very small bits. That's its bread and butter. But keeping it clean long enough to work with pond water is normally a problem. To me, if I suspected pesticides or something serious in the water I'd do a complete water change and not mess around with carbon. And routine water changes reduce risk of accumulating risks solves lots of potential problems.

 

[Meyer Jordan]

I can't address your experiences, but I have used AC, when indicated, in ponds for many years and never had a problem with it clogging up before it was able to perform its intended function. AC produces results fairly quickly.
As for water changes, well I am not going to beat that poor dead horse for now.
Let's just say that we disagree.

 

[carolinaguy]

one of my teachers suggested that when determining the amount of filtration, take the advertised amount and divide by 4. if it says its a 2000 gallon filter, plan on it being 500. the two things you can never have too much of are oxygen saturation and filtration capacity. as for in and out filters, out is so much easier to clean, and you will find that although you thought you would be a koi keeper, what you really are is a fish waste treatment technician. big filters extend your cleaning schedule frequencies, lower the threat to your fish, make the experience more enjoyable. given that you will overstock your pond just as we all have done early in our hobbies, a bigger filter makes a great cushion against your enthusiasm. plants, bog gardens, and side wall filtration capacity can never make up for a larger filtration capacity than you need.