Backyard Aquaponics
A place to discuss aquaponics

So what size delivery pipe do you need for a 18000lph pump?

@1m/s you would need an 80mm pipe to supply 18000lph.



however there will be losses even with short lifts so the pump will be probably doing 15000lph (=15klph =15m³/hr)

so @1m/s you would need an 75mm pipe to supply 15klph.



I would go for @2m/s you would need an 50mm pipe to supply 15klph. (or maybe 14klph with the extra resistance. but its not a deal breaker.)



Also consider that this is a large pump with good head capacity, it may pump to 10m head albeit with much lower flow maybe 2 or 3 klph? a small pump more normal in BYAP say 5 to 8 klph might only do 7 or 8m so the smaller systems are better off with the lower velocity.

SLO's and drains need to have much lower velocities unless you have a lot of downward grade in the pipe. less than 1m/s.

I go from pump to 50mm, which feeds to three individual t's. I will list them in order starting from closest junction to pump.
- 50mm pipe to sump(mainly for aeration), but it is under the water (find this gives better pressure to other pipes), and it has a end cap with holes (to give better pressure to rest). It goes all way to bottom of tank
- second outlet is 50mm to 25mm using a reducing brush, which goes to fish tank. It runs at about 1800lph, but could do more, but I find 50mm SLO outlet doesn't handle any more.
- next (and currently top) outlet is to GB's, which is a T with two growbeds each side. Haven't measured for awhile F&B cycle, but it's numerous times per hour.

I believe I will get a lot more pressure by having return to sump being the "highest" point (even though it will bend back down to sump level), and by adding plumbing to be looped.

Pump is a pond pump that I took guard off and plumbed inline, and height from pump is about 1.5 m, height from top of sump tank (which I think is "head height"??) is 80cm. I think if I plumb right I've got plenty.

As said above, I'm trying to stay away from aerators, so want as much pressure in sump thrashing water as possible.

Thank

Sounds good to me

the head height is from the water level where the pump is to the height of the pipe outlet if it discharges to air.

That's good to know as I thought it was from sump water level. Being inline must help but right? Pressure from gravity/load pushing instead of pump having to suck?

If you have a large pump that pump is bigger than you need then a whole stack of design guidelines/philosophies that focus on efficiency go out the window. So with so much water being moved you don't really need to worry about larger pipes (from the pump) or avoiding venturis like the plague because you have litres to spare and electrons to flow but...

You want this pump to do what most people want a water pump and an air pump to do therefore it may be a good idea to maintain as much flow as you can.

I don't know how large your system/FT/stocking densities are so I'm advising blind a little but...

Why are you aerating the sump?
WHy not send all flow to the FT (and a little to the towers) to give the maximum aeration where it is needed?
If some of the outlets from the pump are just above the water level in the ft then a large amount of air will be entrained into the tank providing lots of aeration.

A problem with this would be you would have to increase your drain sizes. I don't know if this would be a big problem or not

You calculate the static head (the vertical distance the water has to be lifted) from water level to water level. So if your FTs water level is 1m above the sump and the sump is 200m deep and the pump is on the bottom and the sump is full of water then the pump has to move the water against a head of only 1m. Mind you there would also be the friction loss from 201m of pipe.

Personally for small systems I make my delivery pipes as big as I can afford to maximise flow from whatever pump I'm using. For commercial designs with variable speed pumps I do a cost benefit analysis of how much a larger pipe size will cost versus the extra electricity to run the pump at a higher duty.

Currently I am running one fish tank (1000L), with 10 goldfish, 4 grow beds (300L each) and sump. In the next few weeks this will be upgraded to 5-7 GB's, 4 FT's, one sump (1000L). All using IBC's. 4 FT's is for variety of species, not so I can fill all of them up! I want fish side to be fairly low maintenance, so once I work out a plan for fish I will be looking at suggested stocking rates, and go slightly under. Looking at getting freshwater prawns though, wonder if anyone has stocking rates for this

Yeah I have as much flow going to FT as SLO can handle currently, and my GB's fill up as quick as Bell Syphons can handle. Excess to sump. The reason for sump being aerated is I have excess, so want to use it to keep air as oxygenated as possible. When I do upgrade, I will have venturi's in each fish tank, and will have a bit more water coming out (as I will increase pipe size or numbers), and it will be over a bigger area (little bit more spread out), so don't know if I will end up with excess going to sump. I do want to try and have extra aeration in sump, as I would like to supply GB's with as higher oxygenated water as possible.

As always thanks everyone for ongoing advice, love this forum!

Ok...~18,000LpH to a 1000L tank not exactly conventional


Why venturi's? If you do a search on the forum you should find at least one discussion about how inefficient they are (me) versus how apparently good they are (not me).




So is your design a CHOP II ie pumping to both GBs and FTs?

In AP, we're usually not concerned (within reason) with pressure, in fact good system design dictates we keep the pressure as low as possible throughout the system whilst maximising the volumetric flow of that design. The speed at which the water is moving through the system (on the delivery side of any filtration) only needs to be sufficiently fast to keeps solids in suspension; water moving at 2m/s can keep a 20mm steel bearing weighing 32 grams in suspension! If you've got waste this size in your system, then you've got some serious problems!

The place where we want water moving slowly is in the filtration media. In order for the good bacteria to do their work converting the ammonia and nitrites, studies have shown they need to have access to the water for approximately ten minutes. Blasting massive volumes of water through GBs in short periods severely (adversely) impacts the performance of the system. Fine solids held in suspension need to be filtered in the media too, and forcing large volumes of water through small gaps between media particles actually ends up blast-cleaning the media instead of filtering the water! Water should move sedately through the media; unnecessary use of siphons (despite their coolness factor) can also be to the detriment of the system performance. We've seen an explosion recently, in the number of people adding "extra" filtration to their systems through RFF, hydro-cyclone, vortex and swirl filters, scrubbers, paintbags etc; the need for these could be reduced (or removed entirely) with better system design and reducing the speed of water through the filtration media.

A general rule-of-thumb for (non-commercial) AP is to have the capacity to be able to expose of the water in the system to the filtration media once per hour, or thereabouts. If you've got a pump which exceeds the requirements of the system, in many cases it is far more $$$ efficient in the long term to purchase a more suitably sized pump than persist with the oversized model. Compare the cost of electricity over a year for a IBC system with an 18klph (10m head) 220W pump to a 3klph (3m head) 40W pump, especially if the static head in the system is less than 1m. (Now, double the purchase cost of each pump; you need a backup!)

If you have excess capacity with your pump, instead of blasting water back into a ST from whence it came, consider raising the water as high as possible and employing waterfalls, bakki showers or similar for better aeration; a simple system as employed at Fremantle TAFE is a large diameter PVC pipe filled with small PVC offcuts through which water is "trickled" and when it arrives at the FT, it's almost effervescent (without micro-bubbles)! In any case; over-pumping water which may contain larger waste particles will break these particles into smaller particles which makes them more problematic to filter, so is best avoided; there have been many discussions on the shortfalls of the (in)famous CHOP2 design.

Another factor which many people don't take into consideration is for when things go awry. With an oversized pump, the time taken to empty a system of water in a HSM is less than with a correctly sized pump! A little bit more available time might be all that is required for corrective action or better decision making, so is prudent to incorporate into the system design.

In order to maximise flow, keep velocity in spec and minimise pressure, good system design:
1) minimises the static head i.e. the vertical height from the top of the lowest body of water to the highest water outlet in the system, and
2) minimises the transport i.e. the distance the water has to travel in the pipes. Bends, turns, joints, constrictions etc all cost and are added as length e.g. a 90 elbow in 25mm PVC has the same effect on the flow of water as a straight section of pipe about 1.6m in length. Systems which look like the Windows'95 screen saver are going to have higher losses.

These principles are "generally" achievable in backyard systems by preferring to use larger diameter piping in preference to smaller diameter piping. (A counter-argument is that larger fittings are more expensive, but the c-c-argument is that if you design it right in the first place you wont be needing to buy replacement fittings!)

Now, all of this may seem a little off-topic, but it's all related. If you get the right sized pump commensurate to how much water is in the system, layout the components so as to minimise the static height and transport allowing for minimal bends, turns, joins and constrictions, then designers can use pipe charts etc for better effect and minimising the actual pressure throughout the system and the lengths where that pressure is experienced.

In bCasey's system, it might be prudent to use the capacity of the pump to lift water from the ST to the highest point, take off some water for trickle towers and drain these either back into the ST or the FT, and have the remainder fall though an aerating system (waterfall, bakki shower etc) as this will not only increase the DO but also reduces noise. (Although I fear that the pump is still too large and will require extra diversion or throttling?) The highest pressure region (and therefore the point prone to failure) is at the pump which is located in the ST and will contain any burst/leak; the rest of the system is under negligible pressure and gravity fed. If a 50mm SLO has already been installed, then with 1000lph arriving in the FT, water will be travelling up the SLO at more than 10cm/sec which is more than adequate for lifting fish waste and uneaten food.

Sorry if this post reads like it was written in sections at different times -- it was!

Oh so many good points Bunson


That is a new one I haven't thought of before. Even after Bacsey's system has been expanded to 4 IBC FTs 18,000LPH if there is a fail is going to empty things in a hurry.

My alternative to buying a new pump is too build your system much bigger at least a total of 15,000L of FT

Although you might want to check the efficiency of the pump you have. In addition to it being over sized for what you seem to want it is probably less than 30% efficient. Buying a new efficient Laguna (~40-45% efficient) will save you money in the long run. Also as someone has already suggested a second small pump for your towers would also be a good idea. If you only have one pump then you still have to pay for the extra electricity to deliver the water to lower heights at high pressure to get water to flow at the higher heights.

But he did say he was moving his system and expanding it, I think some of the advice given should be more in touch with what Bcasey2703 is after rather than trying to change his system as to what you would do? Once again if someone is having troubles they will ask? But if they are happy with what they have, then it would be best for all if we didn’t try and change their ideas, rather urge them on their way, yes others have made mistakes, but they have learned from them, I hope,

And Stuart, cutting peoples post down to your interpolation of what they are trying to get across is not helping!

When anyone gives advice don't they always tend to suggest what they would do? Isn't that normal.


Didn't this conversation morph from a discussion of a particular table to a discussion of options that are available for Bcasey to choose from? Personally if someone saw that I was doing something that from their experience or education was a bad idea or even not the best idea then I would welcome their input even if I thought they where wrong. Yes people learn from their mistakes but a smarter way to work is to learn from the mistakes of others to save yourself the effort, expense, hardship and heartache.


I've been operating under the impression for sometime now that it is impolite to re-post peoples posts in full. I had though that it was forum etiquette to cut down a quoted post so that it was easier for other readers to follow and understand.

All good Blizzard, I will shout if it's too hectic, the boys are right, but I have my reasons, mostly due to ease of use for myself (perceived or otherwise).

Big posts where a lot went over my head...

But my thought process is as follows

- I am quite "loose" when it comes to overall system design, and like to have the ability to add on without having to think about whether I have enough pressure, whether my pipe design can take it etc. I read a lot, and as I am a bit of an insomniac, try to at least have my late night ramblings be productive instead of just watching tv or trolling Facebook. So if I stumble across something interesting, I want ability to do it. I am not very "handy" in regards to building, but have done everything myself so far, but I would hate to get halfway and have to redo everything in order to add-on. Plus for various reasons, things could end up a little spread out, or impractical/inefficient, for the sake of design. I must admit I wanted extra power to facilitate my whims. Plus I want freedom to add grow beds. Whilst the important and "must have" grow beds are 6-7 number, these are largely for display purchases, and won't be as productive, but I want ability to plug in and go, not have to redesign or reconfigure. I also realise I could go a lower pump wattage and leave some space for growth, but this is a part I really want to not have to think about. My "pipe dream" goal is to have 5-7 GB's for display, but up to ten more for real growing to supplement. An example of my randomness is I have a fascination with ZGT's, I just want some for my own reasons, and height is good for this.

That was a lot of rambling, but I agree I could be a lot more efficient, but I am now on a timeline, and will have to cut some corners to facilitate ease of install, and ability to grow, within the confines of my low handyman skill.

Some more specific thoughts on your post
- good point on emptying quicker in case of disaster. I have (due to unfortunate experience) had system been emptied, but my fish tank is setup so it can't lose everything. I am probably going to over plumb fish tank so that I can minimise these issues where possible.
- I hadn't realised smaller particles were a bad thing. I guess because I have a filter from FT to sump, I am not as concerned about this. Can I ask why smaller particles are worse then bigger? I would have thought bigger ones took longer to break down, and that if their are any "goodies" you are better off breaking them down and dissipating
- the bends and turns etc is one of reasons I like having extra pump capability , as I don't have to think about it as much. Especially where because my system will be a fairly specific build, and will be dependant upon outside issues being more important then efficiency in terms of design, I have lots of scope. Minmising the static head falls into same category. If I decide for aesthetics, or because of where it fits in to surroundings, that I need to pump higher, I want capability. I don't know if I have mentioned in this thread that this system is going into a cafe I will be leasing from this week, and it has to fit in for design of that, compared to making a system which is efficient and productive.
- System is quite quiet, as I have return to sump under water. There is a noticeable noise increase when syphons kick in. Also my pump is inline not in sump itself (not sure if I have said that). I make actually want more noise in future, as next door neighbours may have issues with being successful and customers making noise, and I have used water features to great success in the past mitigating noise. Thats a way off though.
- Once system is in I will post a link to design, and rates etc, for those that are interested in my build thread, and let this thread know.

Thanks very much for everyones input, whislt some of it goes over head, have learnt lots, and hopefully other people have to.

On a side note, one of things I read when looking at designing system is always buy a filter bigger then you need to allow for expansion and experimentation in terms of getting plumbing right........ think I may have taken this to the extreme??? Ahaha

They are and are not worse.

They are worse because big particles are easier to remove/trap so since they are removed or trapped the fine particles that remain are worse mainly because they remain.

Fine particles don't so much kill fish as lower water quality which stresses the fish and makes them susceptible to other infections. Although if the concentration of fine particles is great enough it will kill much like smoke or dust would kill us.

In RAS systems fine particles and a real bug bear because they don't get removed easily and they persist and build up. Screens to remove them are expensive not so much to buy, although that is an issue, but to run because of the relatively massive friction loss through filters fine enough to trap them. Foam fractionaters and other devices do they same job but you still have the expense of installing and running them. Some systems don't bother with the tech option and instead just do water changes.

Media filters if they are designed properly and are subjected to light loads are extremely good at removing all solids including fines. Slow water transit speeds allow large particles to settle on media surfaces and once the media is colonised by various bacteria the surfaces become sticky trapping fine particles as well the large.



If you are returning the water under water then the amount of aeration you will be getting will be seriously reduced.


Yes.

Cool, I am happy with my make shift filter with current stock rate taking care of this, but that does make sense.


Yeah, it is next to someones bedroom so I keep it quiet, new spot in cafe won't have that limitation. Once again noise will be my friend.

Thanks Stu

So question which I think is appropriate for this thread.

I am setting a new system (same system as current just moving). Trying to start my design. In terms of F&D returns, is there some logic to what it needs to be? I currently just run each back to sump in 25mm. But that will be extra plumbing, much easier if I could run all beds to a main drain. So what size drain will I need for up to 7 GB's if I have 25mm drain pipes. I am assuming I will need capacity for when all drain at once, so 200mm? Or because they all won't be draining at one point, but entering drain point about 3m apart will it e ok with something like 150mm. Does this make sense or do I need to do a diagram? Another way to ask it might be what's best way to plumb 5-7 grow beds in a straight line spread out over 18m back to sump?

Thanks!