Pipe Size

[Andy41]

Hi Guys,

I'm not sure if this belongs here, or in pond construction, but since i'll be building my own filters i'll start here.

I have a new 4000 gal pond which i want to turn over 5-6 times a day. I'm planning on using a retro drain connected to a pump that pushes the water first into a vertex to seperate out the waste, and then through 2x 55 gall skippy filters. This should give me a retention time of about 10 minutes.

However, i'm concerned about the pipe size i should be using.... if it's too small then the water will back up in the filters and overflow... right?

The biggest piping i've found here that's easily available is 2" PVC. I was planning on using this for all the plumbing work.... do you think this will be suitable or do i need to go bigger?

Also, what biofilter media do you guys recommend? For my current skippy filter i using a router bit and ground up electrical conduit pipes into plastic spirals. It was cheap, but took *ages*. I'd like to avoid doing this for two filters.

cheers,

Andy.

 

[vertigo72]

Look harder. Sewage PVC pipes are readily available in much larger sizes. Im using 110mm (4.3") between my vortex and biofilters and for the gravity return. I dont think you will need that much with your target of ~1000 GPH, but with just 2" return you would be pushing your luck (capacity goes with the square of diameter, so my 4.3" pipes actually have almost 5x the capacity of a 2"). Another advantage of wide pipes is that the water velocity is low, which helps the vortex.

As for bio media, whatever you can easily get your hands on. Many here use 1" pipes they cut in small pieces, but thats also a fair amount of work. I am using all kinds of stuff, though mostly "real" bio media (as I could buy it cheaply) but also those spiral irrigation hoses that I.. unspiraled. Not sure how to explain, i didnt cut them, I just started pulling at the edge and it winds down. Works great. Those nylon package wraps, if you can source them, apparently also work very well. Or nylon floor scrubbers if you can find them cheaply. Im sure others will chime in with more suggestions, but it really boils down to what you can find for cheap IMHO.

 

[robertmathern]

I just got done with building my filter. I used 2 2" shower drains. I will say both shower drains can handle 1000 gph but not 1 shower drain. The 2" pipe can handle 1000 gph with no problem. On my reef tank I am kicking 2500 gph through my overflows with 2 1" drains with no problem.

 

[fishin4cars]

Hi Guys,

I'm not sure if this belongs here, or in pond construction, but since i'll be building my own filters i'll start here.

I have a new 4000 gal pond which i want to turn over 5-6 times a day.

*** You really need to shoot for a goal of at least 1 turnover per HOURfor a pond, 2 would be better but for sure more than 1/4 a hour, just to slow for most applications. For certain way to low for Koi!

I'm planning on using a retro drain connected to a pump that pushes the water first into a vertex to seperate out the waste,

***3" is the minimal recommend drain size pipe and most folks recommend 4" minimum

and then through 2x 55 gall skippy filters. This should give me a retention time of about 10 minutes.

However, i'm concerned about the pipe size i should be using.... if it's too small then the water will back up in the filters and overflow... right?

****return piping should be greater than the input, If your pumping in by a 2" then 3" or larger should be used for the return and the join the filters.

The biggest piping i've found here that's easily available is 2" PVC. I was planning on using this for all the plumbing work.... do you think this will be suitable or do i need to go bigger?

****2" is good for about 2500 gallons, any more than that the piping really starts reducing flow rates considerably. you can pump higher rates through 2" but the back pressure to the pump is going to be pretty great and it will reduced flow rate.

Also, what biofilter media do you guys recommend? For my current skippy filter i using a router bit and ground up electrical conduit pipes into plastic spirals. It was cheap, but took *ages*. I'd like to avoid doing this for two filters.

****PVC is a option but not one of the best as far as bio-filter. The hard plastic is good for separating but not so good for Bio-filter as the bacteria have very little to actually grab a hold of. Sprinkler hose is far better as it is porous and has far more surface area for the bacteria to grab to and grow on, Bio-balls, bio-barrels, K-1, matala, and Cut up scrub pads,and packing straps or ribbon and are all good options also. The last chamber you could use lava rock or feather rock also. These are great bio-filter media as long as it is not allowed to clog, in the last filter chamber most of the big stuff will have already been removed making it the optimal spot to use lava rock or feather rock in

cheers,

Andy.

One more thing, if you'll use brushes in the top of the vortex this will help greatly in reducing and separate the large debris that make it in to the vortex and keep them out of the bio chambers greatly reducing the need for cleaning the biofilters as often. as far as drains go on these, I recommend using a drain on all three chambers, Of course the Vortex chamber will be needed to be back flushed the most but the other two will need to be also from time to time and it also makes it much easier to drain if a problem comes into play and you need to empty the 55 gallon barrel. 2" is plenty for this, It has enough suction to draw out the muck and will empty a 55 gallon barrel in under 30 seconds, When back flushing either of the filters it's best to back flush them completely, I have found that the most gunk will be removed out of the system as the water level drops out through the media. You'll get a dark mucky water for the first few gallons then it will clear up then as the last 10-15 gallons dump out it will get really funky again.

 

[vertigo72]

On my reef tank I am kicking 2500 gph through my overflows with 2 1" drains with no problem.

Then either you are not taking pump head in to account and its pretty damn large, so your effective flowrate is well below 1000, or you dont mind your water being nearly a foot above the return. I cant find the table with the actual numbers, but Im pretty sure 2 1" pipes would cause a serious "overflow" (height above return) with a 2500gph flow. My 4.3 inch pipe has almost 10x the capacity of your 2 pipes and the filter overflows with a 6000 GPH pump (4000 or so effective). With that pump, I think I got nearly 10 inches of height above the return. Not something you want, especially not when cascading several filter barrels.

 

[fishin4cars]

http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

 

[robertmathern]

Nice flow rate chart there. And vertigo you are right I did not take into account head loss So with a mag 24 after head loss yeah about 1800 gph give or take.

 

[vertigo72]

http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

Interesting chart, but not quite what Im looking for. For all I know, "minimal" pressure loss could mean a foot of water. A foot of head loss may be minimal for the pressurized side, but not so for the gravity return, when water in your filter rises a foot above the return, its usually a serious problem.

I linked a chart earlier that showed the increased in height for given diameters and flow rates, Ill see if I can find it again. Either way, 2 inch pipe for 2500 gph is not going to give you a lot of wiggle room. Id rather play it safe.

 

[vertigo72]

Found another one:

With a 2" pipe and 2500GPH flow, water will be 3-4 inches above the return. Not as dramatic as I thought, but still annoying if your return is 3" from the top .

As for the other example with 2 1 inch pipes and 2500 GPH, thats the same as 1 pipe with 1200 GPH, thats over 12". Thats one foot, exactly as I guessed lol.

 

[fishin4cars]

That's the chart I was looking for Vertigo, just didn't find it.
My next build I was thinking about doing something similar, 1 55 gallon vortex, 2 55 gallon bio-chambers, and adding in a shower type filter seperate from these. My plan is running all the flow pipe after it enters the vortex in 4", this would give me extra flow in case I had to upgrade later on and allow as little back pressure as possible. 4" is about the largest available pipe and fittings we have in this area, any larger and I would have to special order everything, which would be a pain if I missed something or needed to change design while building.
Intake side I'll probably go to the vortex with what ever size the pump is set up with with a relief valve back to the pond in case of to much flow and that way I can adjust as needed. Question I have been wondering about, On other sites a lot of recommendations are that the filter's should be about 10% of the actual pond volumne. So how much fish load and what size pond would be safe to run on a three 55 gallon chamber system in optimal conditions? If I'm understanding correctly this would mean that that size filter is good for 1100 gallon pond or 1650 gallon pond? not sure if the vortex would be considered as part of the bio-filter or not.

 

[robertmathern]

I was just using my tank as an example. The tank is fine unless a snail gets in there then I might have a problem. However I just trying to give an example that at 1000 gph a 2" pipe will be plenty.

 

[vertigo72]

On other sites a lot of recommendations are that the filter's should be about 10% of the actual pond volumne. So how much fish load and what size pond would be safe to run on a three 55 gallon chamber system in optimal conditions? If I'm understanding correctly this would mean that that size filter is good for 1100 gallon pond or 1650 gallon pond? not sure if the vortex would be considered as part of the bio-filter or not.

I think you should read that as your entire filter should be ~10% of the pond. Of course thats just a ballpark figure. For small ponds, it should be more than that, and for large ponds, its probably way too much. FWIW, you know the size of my pond (~12K gallon), and Im still filtering with just 3 55 gallon barrels (one vortex+brushes, one vortex + large PVC pipes, one biomedia) and I have way overcapacity from a biological filtration POV with just one barrel of biomedia.

HOw I know? because I shut down the iris bed for over week to waterproof its borders, so I only had my 3 barrels (and precious few plants in the main pond), and no matter how much I fed, I consistently measured zero ammonia, zero nitrites, and interesting, zero nitrates. Ive never really measured anything else TBH. Of course if you intend to fill it with 100 adult kois, that would change everything.

I think a better measure is the volume of biomedia and how much ammonia that can convert. I did that math in a different thread, I just cant find it anymore. 60 liter of K1 kaldness could convert 35? mg of ammonia per day? Dont recalll, let me see if I can find it again. But that way you can calculate roughly how much kg worth of koi it can handle. Thats more important than pond size.

 

[vertigo72]

I was just using my tank as an example.

Well, its still interesting, since it shows that either you have 8" of water over your return, or (more likely), your actual flow is much lower than you thought. Perhaps you should measure it.

 

[vertigo72]

Fishin, cant find my posting, but I googled some numbers again.

Kaldnes K1 has been proven in fish farming with feed rates up to 0.75kgs of 40% protein food per 50 litres of media per day. Evolution Aqua is rating it at a maximum of 0.25kgs of food per 50 litres used, in order to ensure the best possible water parameters are achieved. If a higher feed rate is required, extra media can easily be added.

Koi are typically fed at between 1% - 2% of body weight per day. Therefore for every 5 grams of food fed. 1 litre of K1 media is required. At Evolution Aqua, our filter designs are based on the higher rate of 2% per day

http://www.cascadekoi.com/Koi/EvolutionAquaKaldnesK1.aspx

Now assume cut PVC pipes are 5x worse than a floating bed of k1 of equal volume (thats a pure guess) and you have a ballpark figure how much bio media you need for your amount of fish/food. Say 1 liter biomedia per 1 gram of food per day or 30 gram of koi. With 110 gallon of biofilters, thats, ~500 liter, that would be good for around 15 KG or 33 pound worth of koi.

Note thats purely for ammonia and nitrites, but you know that. To keep it clean with mechanical filters, it all depends on your pond and situation. Ill tell you I dont have enough filtration for that with 1.5 55 gallon barrel, but I dont assume you intend to build your pond in the middle of a forest like mine

 

[robertmathern]

Well, its still interesting, since it shows that either you have 8" of water over your return, or (more likely), your actual flow is much lower than you thought. Perhaps you should measure it.

Trust me I get off work here shortly and when I get home I am going to measure it. Now its stuck in my head as to why I have never had a flood. How can you actually measure flow in the tank or just measure the amount of piping and calculate it from there.