Large pond filtration system

[swill]

This is the first stage of a multi step plan to renovate my backyard pond. My goal as a pond-keeper is to enjoy simplicity and stability. As water quality is paramount to the success a pond micro-ecosystem I decided to start by adding a bio-filter. I wanted to complete this project in short order on a modest budget. I chose to use 3” diameter pipe due to increased volume of flow and a faster turn-over rate. The sump pump is located on the bottom of the pond floor vertically, fitted with a ¼” wire-mesh guard around the intake (secured with a bungee). The pump output was modified to accept 3” pipe by using a reducer. This water is pumped approximately 5 feet of vertically, with a modest 30 degree rise out of water to a bulkhead in the side of the tank. Water then flows downward past the venturi (not sure if installed correctly) and to a T that splits flow to each end of the stock-tank, ending with 90 degree fittings at opposing angles to create vortex like current. The water rises through the filter media and mesh. Lastly the water exits at the end of the tank though a 4” bulkhead, and 4” 90 gravity feed through 4’ of pipe.

So far I have filled it up with the treated muni aquifer water. Turned on the bio-filter with its Harbor Freight sump that has a 2.5 year warranty, realizing it may or may not last 24/7 operation, hopefully it will work until I can afford an external pump. Everything is flowing well and working as planned so far. Placed some potted elephant grass plants in the bio-filter to hold the swamp cooler filter media down. I know the biological processes requires time to develop the healthy bacteria that process fish waste in my filter, but I’m still skeptical if this filter alone can treat 10,000 gallons of water adequately. My predication is that the water will eventually go through phases just as it always has, water clarity will vary as the environment changes seasonally. My hypothesis is that as the water ages, and my fish populations expands with twice daily feeding, water clarity will decrease.

In order to mitigate any potential future water clarity issue, I am thinking proactively. The water fall/skimmer setup should be an effective way to remove large derbies from the surface, as the bio-filter should work for the smaller solids pulling from the bottom. I’m thinking of adding additional media to the bio-filter to handle very smallest solids that can be removed mechanically. I’m skeptical however of all the marketing hype of different filter media, additionally retail prices range from expensive to outrageous. Wondering if just adding an additional layer of the swamp cooler media is all that’s needed?

During my research and planning phase of this pond-redo project I came across many DIY builds of various sieves, vortexes, settling chambers, and phoam phraxionators. Affordability is critical in order to make any further major improvements and/or additional systems. Adding another bio-filter as this point would be redundant as my stocking levels are very low, and the screening system removes everything larger than a 1/8” well.

Considering dissolved organic compounds could cause future clarity issues once the bacteria on the pond surfaces fully develop and fish increase in size, proactively I am interested in potentially building a phoam pharaxinator. However adding DOC removal is problematic due to having to install it on the output from the skimmer circuit, and due to aesthetics as well as height limitations resulting in not being able to route the pharaxinator output to the waterfall, thus adding a third return line and additional pipes.

The other option under consideration is UV light treatment in the pre-filter stage, however this would be difficult the 3” pipe and relatively fast flow. Also not too excited about additional electricity consumption and future bulb replacement cost. Could place it on the water fall/skimmer circuit, but currently the circuit is only run occasionally or when needed to save on energy cost.

Suggestions?

Filter System:
Vortex Type 150gal Bio-filter
Input; 3” PVC from bottom of pond
1hp 4000GPH (approximate) harbor freight submersible pump
(2) 45 degree 3” fittings PVC
(3) 90 degree 3”
venturi 3” to 2” open PVC
2” grate cover
(2 ) 10’ black schedule 40 PVC
Three-way “T” 3” PVC
Swamp cooler blue role filter media
Galvanized aluminum lath sheet

Waterfall feature:
Input; 2” PVC skimmer feed
½”hp 3700GPH sump 6’ head
Home-made 2 size wire mesh skimmer
¼” aluminum grid wire
1/8” stainless grid wire

 

[DrDave]

Welcome to the forum.

 

[hewhoisatpeace]

I've got some ideas to help. 1st, http://leisure.prior-it.co.uk/venturi-pond-aeration.shtml check this out.

2nd, foam fractionator is the way to go, getting DOC out will be far better than just killing algae for water quality.

3rd, pond looks great, but 150g biofilter will be way too small, plus your media is not sounding good. Try strapping, you can find a lot of info on it here at this site, will provide much more surface area for much better price.

Gotta go now, I'll write more later.

 

[swill]

Thank you for the input so far. I'm pleased to report, water to date has been exceptionally clear. Could just be the time of year. Way to early to make any definitive conclusions. So as I consider my options for future improvement, the DOC may be the next target. As all retrofit installations go, complication factors exist. If I add a 3-way valve of the skimmer line, and direct to the top of a phoam phraxionator, I can run the return lines back to the pond by gravity, feeding two underwater jets to generate current. Should this be my next step?

 

[DoDad]

If you have the proper sized filtration, fish load and waterchanges you won't need a foam fractionator.

 

[Pondmaster]

DoDad is right on. Foam fractionators/protein skimmers are not needed and really work better in marine aquaria where the water density is heavier.

 

[swill]

If you have the proper sized filtration, fish load and waterchanges you won't need a foam fractionator.

Clearly stated above, I expressed my concern over the size of my newly installed filter setup. My pond is approximately 10,000 gallons and the filter is only 150 gallons. My flow rate from the 1 HP pump is roughly 4000 GPH, so that is a turnover rate of 40% per hour. So, what is the general consensus on a properly sized filtration system?

My fish load is minimal currently with a small amount of fish; 6 goldfish, 4 bluegill, 4 striped bass, 1 hybrid carp, and 5 catfish. All the fish are small in size, none over 6” long. I’d like to add koi to the mix, but I’m not sure the conditions are right yet. I want be sure the pond will be somewhat stable.

So if DOC removal is not needed at this point, should I just increase the feeding frequency and possibly add more fish and see what happens? What about adding water current to mimic a river flow? Will this help with fish vigor and growth? Point me in the right direction. What are should my next steeps be?

 

[Pondmaster]

swill,

Some, not many, ponders use no filtration and depend on low fish load and water plants and are successful. the 40% turnover rate and the 150 gal biofilter is fine until the fish load becomes heavy which is definitely not the case here. You stated early on that simplicity and stability is your goal, I would say that a natural bog filter produces better results in fresh water than foam fractionators/protein skimmers.
My fish love the over 5,000 gph flow off my waterfall. Remember that in addition to your 150 gallon biofilter the whole pond as it matures acts as a filter carpet algae etc. Will you have a water fall? if so this also helps with filtration. Your bio-media in your 150 gal is a big factor also different bio media have different surface areas. I use matala rounds and love it others on here have great success with other media.

You will have to use some discernment as you read the view points / answers here.

 

[Pondmaster]

One other thing flow rate through your 150 gal filter is important. I flow at 2900 GPH through 18" of matala in a 22" round 65 gal container and that works great for me. Just make sure that the flow is not too swift. Many factors enter into having the correct flow and I haven't seen a chart that would help, maybe someone here has one. I also flow 2400 GPH through a loaded up with media Laguna Filter Falls. I really don't need that much flow or filtration for my moderately stocked pond but I run one pump as a bottom filter and one on a no-niche skimmer

 

[swill]

One other thing flow rate through your 150 gal filter is important. I flow at 2900 GPH through 18" of matala in a 22" round 65 gal container and that works great for me. Just make sure that the flow is not too swift. Many factors enter into having the correct flow and I haven't seen a chart that would help, maybe someone here has one. I also flow 2400 GPH through a loaded up with media Laguna Filter Falls. I really don't need that much flow or filtration for my moderately stocked pond but I run one pump as a bottom filter and one on a no-niche skimmer

This is all pure conjecture at this point but I think the my current flow rate from my sump-pump is good considering the total volume of the pond. I thought an ideal turn over-rate for my stocking level would be right around once every two hours.

The bio-filter media situation looks to be the weakest link in the chain. I’m going to add some strapping in media bags and possibly another layer of matala type media. That should provide much more space for the bio filtration process and impede the flow.

Another option I’m considering is adding a second 150 gallon filter chamber in-line with the existing to effectively double the filtration capacity and further slow the flow. The first tank would be more of a solids and fines removal stage and the second would function as the bio filtration and settlement step.

Also considering ditching the 1hp pump altogether and getting a mag-drive type submersible pump. Lower energy consumption, only 18” of max effective head on my system anyway, and maybe the reduced flow would actually be a good thing considering how quickly the water is moving through the bio-filter.

I really need some definitive recommendations before I invest anything more. Anyone out there with a similar situation or experience? Please chime in.

 

[swill]

Update: Changed out the Harbor Freight 1HP for a home depot 3600gal GPH pond pump. Flow is the same on the 3” pipe into the filter. Old pump was drawing 7 amps! The replacement is only 3 amps. Also switched out the waterfall pump for a 1/2HP stainless waterfall/pond specific type to replace the 1/2HP sump. I’ve eliminated the threat of leaky seals and lowered my power consumption dramatically.

The water is maintaining clarity, however algae is starting to slowly develop on all the pond surfaces as expected. I’m going to try and change out at least 5% of the water weekly to help keep a good balance. Still not sure what to do about bio-filter media, information overload. I know I need to add another layer of some kind of media to complete my filter, just not sure what is most cost effective. Would like to use media bags to facilitate simple media removal and cleaning. I’m leaning toward getting some bird netting and for a bag and adding strapping material as the media. Once I get everything in place I will add more photos and updates.

Thanks for the help so far,

swill :beer:

 

[DrDave]

Use the KISS method. Go look at my web page. Most folks over do their filtration.

 

[cauzeneffeckt]

as far as foam factionators go.. (Im by no means a professional) but DOCS always exist.. regardless of type of filtration, water changes help a ton, but filtration does little in the way of removing DOCs...

 

[cauzeneffeckt]

heres an article so you can learn a bit more about docs.. and you can make a foam factionator for about 100 dollars.. (I just read you have a 10000 gal pond??? is that correct? still can make one for under 200 i believe)

DOCs revisited


Posted by James P on 2/17/2007, 12:01 pm
http://members4.boardhost.com/koimag/msg/1171717287.html

It looks like the organic management thread has hit the wall in terms of stimulating interest? But it is probably THE most important topic when it comes to koi pond management. Certainly for the intermediate and advanced hobbyist this is a more important discussion than ammonia conversation or pH conversation as those parameters are easy to master and subjects for beginners. And maybe less understood- it is organic waste management that ultimately affects ammonia output and pH threats.

Organic issues show up in much more subtle ways however. But they represent a ticking time bomb that can quickly/eventually cause disease, parasite proliferation, a weak immune system thru low level stress, pH crash, gas ration issues etc.

Some of the common warning signs that things are getting out of control are:
Chronic high nitrate levels
Chronic low ORP
Chronic string
Nagging nitrite levels
Yellow water
Cloudy/murky water
Sluggish fish behavior
Odors from the sump
Falling pH
And foam on the water surface

From all these things, we can create two sub-lists. One is the physical manifestation of a eutrophic environment as it moves from low organic load to high organic load. This is of course, the nature of a closed system and as such, is inevitable. It is a form of ‘aging’ as the biology does its thing. This causes a gradual shifting of the microbial mix until an imbalance and/or new dominating species results. Additive intervention in the form of strong oxidative chemicals (chlorine, PP or ozone) ‘clean’ some of the ‘aging’ conditions but not all, creating an imbalance of its own making in the process. So that is certainly not the answer to managing organic trends.

The evidence of this process of ‘aging’ or eutrophication trend is seen environmentally when the water becomes cloudy (bacteria bloom) or the water becomes green (single cell algae) or string algae begins to grow inches per day. This is the physical ‘world’ changing within the pond.

The second list would be the byproduct of such a trend. These are chemicals, proteins or dyes released BY the above mentioned environmental shift. And these show as stained water (yellow humic acids), nagging nitrite (denitrification), chronic nitrate (over active biofilter) or foam on the water surface. All of this in turn, results in sluggish or moody fish (loss of appetite and bottom sitting).

Among the indicators in the second list I’d like to discuss DOCs as that is the number one sign of excess organics in the water column. DOCs will quickly come and go based on pond design, feeding technique, turnover rate and stocking levels. DOCs (Dissolved organic carbon/compounds) are nothing more than ‘the leftovers’ from either fish digestion or bacterial/algal activity. It is a catch all name for molecules of protein, carbohydrates, lipids, starches, sugars, amino acids, fatty and organic acids, the molecules of color food, dyes, hormones from fish and algae and of course humic acid
(which is what stains the water) etc.

These items are too small to filter out mechanically or settle out. In fact they are resistant to settling as they are ‘electrically charged ‘to float towards the surface where forces of thin layer of ‘skin at the surface’ attract them. There these tiny components gather and foam ‘rafts’ of organic and vitamin rich organic material. This in turn attracts free swimming heterotrophic species called ‘wolf packs’ that attack the nutrient source and perform the first step of biological decay- mineralization. This in term feeds protozoa that fed on those bacteria. These all becomes part of the general biomass (along with fish and biofilter bacteria) that is pulling down water quality and reducing oxygen and increasing other species of nitrogenous waste materials and gases. And as will all pollution factors in the water, depending on extent, these things will cause disease or infestation or simply reduce the growth of koi in both size and color development.

It is unfortunate that the beginner is told that ponds need to be given a ‘good cleaning’ twice a year because the filter is ‘asleep’ in winter and the waste accumulates. It is really just another stress factor for the fish at that point. A point when winter exhaustion has the fish slightly or greatly weakened depending on winter care techniques.

Instead of this approach, it is probably better to advise the beginners within your chapters to maintain the organic issues 365 days a year with a regular weekly and monthly routine and to incorporate the latest technology for organic waste management. I think it would be very wise for chapters to spend more time on proper stocking guide lines and proper seasonal feeding techniques in order to manage what goes into the pond and how the pond can be run efficiently.

Running long as usual. DOC removal in another post. JR

*Well, you can't stop DOC from happening? It is a natural byproduct of koi activity. You can manage it and remove it, but not prevent it. I think you mean manage when you say 'prevent,' right? JR