Pond filtration question

rainbowcharmer

rainbowcharmer

AC Members
Jul 30, 2007
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East Coast, USA
So the pond books that I've been reading while planning and now building my pond are all very conflicting on filtration needs for the pond. I'm estimating pond gallonage to be around 2500, and I'm planning to use a rubbermaid stock tank as the filter with water pumped up from the deep end of the pond to the filter and then back into the pond via waterfall.

My question though is how big does the stock tank need to be. They come in 50 gallon increments I believe. The local store here only carries the 100 gal stock tanks ($70). There's one within driving distance that carries smaller and larger sizes, so I can get a different size, but need to know how big I should go.

Is the size of the stock tank directly related to how well it filters? Or is it more of a question of how much water flows through it that really matters? I believe I need to pump at least the capacity of the pond through a filter once per hour, right? So if I get a 2500 or 3000 gph pump, that should be sufficient I think.

The pond will be pretty heavily planted with a variety of floating, potted, and deep-water plants, which I know helps with nitrate consumption, but how do I determine the size of the filtration container?

Thanks for any input!
 
these folks:

http://www.tadege.com/wakinfilter.htm

use DIY filters based on a single 40 gallon trash can (if I'm recalling accurately) for 2500-ish gallon ponds

a DIY filter based on a 100 gallon stock tank ought to have more than enough capacity for you 3000+ gallon (admit it -- you're going there) pond
 
LOL - no. I can't do 3000+ gallons. Hahaha. I do think it will end up between 2500 and 3000 though. We'll see. :) Depends on how hard the digging gets as we get the "deep end" done. If we can get it to 4' like planned, it will be near 3000 gallons.

So would a 50 gal stock tank do you think be OK or should I stick with 100 gallons? My hunch is that the flow is really the more important part of this - that I can push enough water through it to fully filter the water once every hour, but I'd rather err on the side of caution when setting this up initially so I don't have to change it later.
 
What happens to a bog filter in the winter time when the plants either die or go dormant? How does the pond continue to be filtered? In GA, we typically don't get cold enough for the water to freeze over, so the pump will likely be running year round. What I may do is combine the two - I want a waterfall, which is why I'm planning to do the skippy's filter, but I also want to hide it with plants. probably I'll use bog or marginal plants IN the filter itself to duplicate what the bog would do anyhow. My main question now is what plants would work well in that setup (swirling water, rather than calmer water)? The location of the filter will be part to full sun (some shade mid-day, but sunny morning/evening).
 
regulatory warning: it doesn't get cold enough where i live for all the plants to turn brown and stop growing, so this is theory / reading.

the biological filtering action by the bacteria on the gravel will continue to convert ammonia ==> nitrite ==> nitrate, but if all of the plants have shut down completely I guess you'll be left with algae to eat it. if it gets cold enough to do this, your fish should also have geared down to a very low metabolic rate. stop feeding them

there's always a high water flow rate in a bog filter -- you're still turning the tank 1+ times per hour through it

re: swirling water, if the plants are in pea gravel, the water isn't going to be swirling around them; the gravel forces it to take a least-resistance straight flow from the inlet region to the outlet.

if your design has the gravel elevated by a grid over the inlet pipes, a plant that sends roots that deep it will decide for itself whether it can extend into the environment there

whatever you do, avoid using a mint -- with basically unlimited water supply, it will grow to envelop the pond, your yard, your house, . . .
 
"mint" is a family of plants (genus mentha). they generally have crinkley heart-shaped leaves, little blue flowers, and are very aromatic when crushed. you're probably familiar with the extracts of three of them -- regular mint, spearmint, and peppermint, and maybe catnip.

all mints grow pretty much without limit as long as they have enough water.

there is a particular species -- very originally named mentha aquatica -- that grows in shallow water and marshy soil.

since a bog filter is essentially a hydroponic growth medium rather than an actual bog, a lot of plants will grow there besides true bog plants. i would guess anything that didn't need to have dry roots during its dormant period.
 
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Duh. I know mint is a plant. I should have realized that is what was being talked about. I was thinking that we were on equipment and I couldn't figure out what on earth a mint was in the world of pond filtration. LOL
Now I feel dumb... :D
 
speaking of mint, I have some. It is a nasty invader, although I never thought of planting it in the pond. Is it poison to the fish? the mint is ok for them? I guess I am just asking because mine has a very strong scent when pulling it. I finally planted it between my house and the gravel driveway so it couldn't escape, and it is THRIVING in those gravel rocks, that is how invasive it is! I guess I never thought of putting it around water because it struck me as drought tolerant plant that would rot if it had too much water. Also come fall wouldn't it have a messy die back and lots of small leaves in the water, would that be ok? I would really love to hear any other experience with mints, pretty please!
 
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