Backyard Aquaponics

SLO Design Questions
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Author:  Los Angeles Will [ Nov 21st, '20, 07:49 ]
Post subject:  SLO Design Questions

Here and elsewhere, I have seen people use a T at the top of an SLO. I have used this myself, and am happy with how it works. My understanding is that it prevents a siphon from forming and emptying the tank, and serves as an overflow if the Upright SLO pipe clogs.

I was wondering if this would work? Or, if anyone has used anything like this successfully.

What if a 90 degree elbow had a hole drilled or cut into the top? It would still let the plumbing breathe, and could take some water in the event of an overflow.

slo top fitting.jpg
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I picked up a grab bag of 3 and 4 inch fittings, that was contractor excess, but it is one T short for what I was thinking of doing. So if this would work, it would give me enough T's.

Author:  skeggley [ Nov 22nd, '20, 03:03 ]
Post subject:  Re: SLO Design Questions

114 views and no replies? Cmon folk get involved!
Yes Will it would work, as you correctly said break siphon and overflow but also fish escape. ;) Remember the SLO needs a higher outside water level to create good suction at the bottom to remove the solids. What design are you using at the base of the SLO?
The top hole/s can go anywhere on the top horizontal pipe and there’s no need to glue the pipe work within the pipe so it can be changed out if you choose.

Author:  Los Angeles Will [ Nov 22nd, '20, 07:07 ]
Post subject:  Re: SLO Design Questions

Hey Skeg,
I was thinking of going with a 4-3 in reducer, the grab bag of fittings I got, literally a big trash bag, came with quite a few of them. I would notch out about 1/2 inch cuts, or maybe a little more at the bottom for inflow.
SLO base .jpg
SLO base .jpg [ 63.46 KiB | Viewed 2702 times ]

I didn't think about the hole at the T , or elbow, being a possible fish escape route. Fortunately the fish that will be moving in are bigger than that, but I could do it temporarily, and change it out at a later point.

I have used a length of notched pipe to the SLO upright in the IBC system, and it works pretty well, but solids do accumulate every once in a while. I have been trying a different, slightly less protein content feed, and the fish produce a different type of solid, that is finer and that floats less. It seems to clog less.

Being that these are round tanks, an exit at the center seems more appropriate.

Any thoughts about how to transition from the SLO's to the rff?

SLO OUTFLOW .jpg [ 57.26 KiB | Viewed 2702 times ]

Can I have the two tanks go to the one RFS/RFF?

1. This is a big one, since I would have to drain the tanks to move them if this doesn't work out. I would think it should or could work....If the plumbing is joined. I was thinking of trying the over top entry, with a baffle to slow the flow. (I picked this up from Web 4 Deb's video.) BUT, and it's a big one, I don't know if I have enough height to pull off a top entry, so I might have to figure something else out.

I only have two 3-inch uniseals, which would be going on the fish tanks. Maybe the RFF tank could be notched so the pipes wouldn't need to set directly on top.

2.Can my plumbing be 2 inches from this point on?
According to a chart that I saw floating around the web, 2 inch should be able to handle the flow.

So it would be something like 3 inch SLO to RFF to 2 inch RFF exit, to MBBR, to 2 inch exit, to 2 inch plumbing to grow beds...

I have quite a few 2 inch uniseals and bulkheads to use.

Any input or ideas are welcome.

Thanks for the cheer leading Skeg! Lets bring the forum back!!! :)

Author:  skeggley [ Nov 22nd, '20, 07:54 ]
Post subject:  Re: SLO Design Questions

Yep, all looks ok to me, as long as you can regulate the inflow to the ft’s joining as per dwg should be fine but may be noisy as it makes and breaks siphon.
On my round tanks I have dished the ground before seating the tank. One I had to make heightened to tie it in so I used a circle of bricks the same diameter as the base, just loose, and filled it with dirt, well clay here actually, and had a fall to the centre of the circle prob about 1” in your antiquated measurement right where the slo sits. I never have solids build up in any of these tanks, I do however occasionally need to increase the velocity in the slo to remove solids in the upright. I also had to cut 2 uprights as I forgot to add this extra 1” doh.
I hope this answers your questions and I’m sure others would like to chip in with suggestions.... hint hint.

Author:  Los Angeles Will [ Nov 22nd, '20, 08:33 ]
Post subject:  Re: SLO Design Questions

Haha! I will try to be more with the times on my measurements, but it's hard to teach an old brain new tricks...Ok, I am feeling closer to a resolution....Thanks! I raised the tanks 2 inches higher than the grade to create a little more drop....There I go again, d'ohhh. 50 mm higher...

I used something that ha my wife questioning my sanity......but I think it will be fine.

I used 50 mm rigid blue board insulation. I had a lot of thoughts were that the even pressure from the weight of the water would keep it uniform... without squishing it.....
It seems to be much more susceptible to focused pressure in one spot.

Author:  Rcmaveric [ Nov 23rd, '20, 02:23 ]
Post subject:  Re: SLO Design Questions

A couple of thoughts for you. The reason for the Tee fitting is to adjust the water level above the drain opening for the SLO. Which is needed for adequate flow rate. More flow means better vacuuming effect. You see I and probably most others didn't think about flow dynamics and gravity pressure and put the sump at the same elevation as the main tank. For slow systems thats fine and if your system is flowing slow enough then that 90 with a whole big enough to break the vacuume then it will work. How ever, when water is flowing into the hole you aren't vacuuming the bottom. Slower flow rates mean weaker vacuuming effect so bottom of tank won't be spotless and heavy particulate will be harder to remove.

With a flood and drain style system won't really see your tank level fluctuate that drastically because it has time equilize. But if you put a bypass in for a return sprayer to help aerate your tank you will see a flow rate increase and the main tank level rise. In the summer i like all the aeration i can get and it can raise my water level 4 or 5 inches. Remember when water is flowing into the top opening then it is no longer a slow.

So anything can work with caveats and with in reason. I say go for it if it fits the bill. but there is always catch 22 you didn't see till a year down the road or 3 months in and you notice a strange problem.

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Author:  Los Angeles Will [ Nov 23rd, '20, 05:26 ]
Post subject:  Re: SLO Design Questions

Thanks RC!
That is an interesting bit about the T allowing the water to rise, ultimately creating more suction.
I hadn't realized or thought about that part functioning that way.

How's your system going RC? Updates? Pics?

I think I am just going to go with the T. I picked up two garbage bags full of fittings, but had only gone through the 3" bag. I went through the 4" bag today, and found a 3 inch T! Score!

I'm still wondering about the flow affecting everything.

I looked at my pump specs again, and it should be pumping a little over 1000 gph (3880 LPH) at my head height, but a lot of people say they get higher flow rates than advertised with these pumps.

My plan is to split the line to both tanks, which should essentially give me 500 gph (1890 LPH) to each tank.

Each tank is over 400 gallons. One around 400 (1500 L) , and the other around 475 (1800 L).

Before I drill the holes.......Do I really need to go up to 3 inch (76 MM) at that flow rate, or would I be able to get away with 2 in (50 MM)?

Also, I'm worrying that the retention time might not be long enough for solids to settle well in my standard blue Drum RFF.

Also, I don't want it to overflow.

It probably only holds around 40-45 GAL (150-170 L) of water because I fashioned a cone into it.

From here, I was hoping to drop to 2 in (50 MM) between filters, and to the beds, just for practical matters. (I already have a lot of what I need.

Or, should I have an overflow on the fish tanks, going back to the sump to lower the flow through the RFF?
Maybe I could do a sieve before the sump to catch any solids that make their way through.

Author:  scotty435 [ Nov 30th, '20, 05:39 ]
Post subject:  Re: SLO Design Questions

This might help - has a description of how I setup my SLO intake and a picture of Tori's which is basically setup like mine. The larger area of the net pot helps keep the intake from getting blocked. My tank is round and the intake is a single pipe going to the bottom at the center of the tank.

Photos are on the page it's linked to and my description is on the preceding page.

Author:  Los Angeles Will [ Dec 4th, '20, 11:05 ]
Post subject:  Re: SLO Design Questions

Thanks for the link Scotty!

On yours did you end up putting a bowl in the basket? Or do you ever end up having problems with solids accumulating inside the upper portion of the big basket, by the bucket lid?

Author:  scotty435 [ Dec 5th, '20, 05:00 ]
Post subject:  Re: SLO Design Questions

I didn't wind up putting a bowl in the basket Works well enough without it, although, I'm not too picky about the bottom being spotless. I do think that either the bowl or the addition of an air ring over the SLO intake could be an improvement but I don't find I need them enough to add them.

So far no problems I do occasionally remove some leaves from the tank using a net but even with those it hasn't blocked up enough to cause problems. Aquatic snails do get inside the net pot portion and in late summer they might be an issue if your fish don't eat them - I grow bluegill and they do eat the snails so no problem with snails because their numbers stay low.

Author:  Los Angeles Will [ Dec 24th, '20, 07:14 ]
Post subject:  Re: SLO Design Questions

So, Lots of things have been going on, and I have still been lagging it. I haven't enlarged the holes for uniseals yet.
I haven't run the plumbing yet.

BUT, I have been thinking about it....and, it's the thought that counts....right?

Originally, I wanted to use 2 inch (50mm), and have the pipes T off the main line, dumping into the grow beds, with ball valves to adjust the flow. I kind of decided to go bigger for better flow, just in case.

Here, 2 inch ball valves are around 8 bucks, so I'd get going for 30 dollars or so. I think I might even have one or two hiding somewhere.

Now, 3 inch ball valves are much more expensive, and not readily available. They seem to be 30 dollars each or more depending on the source.

Any ideas on how to control the flow on 3 inch pipes that won't break the bank?

I thought about reducing to 2 inch valves, but it just seems like the reducer would create a spot for junk to build up, though the water should be pretty clean if all goes according to plan....

What do you do?
For all of you using 3 inch, 3.5 inch or 90mm plumbing for an SLO, what do you do where the plumbing empties into the grow beds?

Author:  Rcmaveric [ Dec 25th, '20, 03:39 ]
Post subject:  Re: SLO Design Questions

Sorry for the late response. I am deployed over sees at the moment. My system is in the wifes hands.... I pray daily for those poor fish. Last deployment my wife killed 30 catfish that were 7 months old. This time she has 40 blue gill that are a year old. Luckily its winter back home and the system is outside. They should be practicly hibernating until I get home to rescue them from the clutches of "Elvira" (showing my age with cartoon references). Every thing was good when I left. I just need to replace some old green pepper plants and more herbs. I harvest a bunch of herbs. First time harvesting herbs and I was amazed how small they harvest was after drying. I got mint and basil for days now though. Two arm loads of basil and mind dried down 2 samwhich bags packed full

Hopefully in a few more years I can buy a house and settle down and build my dream system.

Back to topic:

Fluid dynamics is a fun thing to grasp. I have a half clue due to working on hydraulics. Your pump is going to move as much water as its rated for. Pipe diameter is going to affect your pressure. Remember putting your thumb over the garden hose.. anyways input lines I use 3/4. It matches the fitting the pump came with. I wouldn't worry too much about the input lines because they will be pressurized by the pump and black lines will prevent bio growth (1 inch lines are easier to clean though). You could step up the line size to decrease pressure but the 1000 gph rating would be the same. Every split and every reducer induces back pressure and you will loose some rated flow. You might not notice if done a couple times but if you plan on expanding and depending on how. One thing you will notice is length and unlevel... water takes the path of least resistance like electricity. So you will need ball valves to balance it all out. I found this out the hard way balancing the flow to 4 grow towers. Was a fun experiment and worked with daily effort.

The reason for the large slow drain lines is they offer little back pressure to maximize the gravity feed. You could go larger. I cant remember if I have 2.5 inch or 3 inch. But I know its bigger than 2 inch. You shouldn't need any ball valves unless your putting in bypasses.

If you want more tanks. I personal would go with each tank feeding into its own solid settler and they could combine into a single sump or their own. Then pump the sump up to the grow beds and let gravity flow it through the grow beds and back into the tanks. Only the pump lines would need ball valves. Small tap offs for prayers into the main tanks. I use bell syphones so that helps air rate the tanks. I also have air stones. It really doesn't take much. You just need to break that surface tension of the water. How ever you choose to do it. You can't actually inject more oxygen into the water unless you use fancy industrial systems and science with pure O2.

Whats nice about that design is during hurricane [CYCLONE] season and I loose power. I use a car battery and bilge pump to cycle the tank a couple times every few hours and don't feed them. Little suckerd lasted 2 days. I wad worried. But they made it.

My dream system is 2 or 3 IBC half buried, 1 IBC fully buried as the sump. Then ply wood grow beds waste high in a green house. Spaced so I can walk around all sides easily.

I got a dream man cave/green house planned out the size of my dream home.

I have also thought of putting my fish tanks above the grow beds. Then letting them gravity feed into grow beds via solid settlers. Grow beds drain into sump that pumps it back into the tank. That seams the best way to do it because then the pump only feeds the tanks and it sprays in to aerate the water no need for tap offs and fancy plumbing.

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Author:  skeggley [ Dec 25th, '20, 08:29 ]
Post subject:  Re: SLO Design Questions

My system is in the wifes hands.... I pray daily for those poor fish.

Too funny. :laughing3:
Will, It’s all about velocity, when you step down in size the velocity increases. Enough to push waste through? Not always.
As you know I have 90mm pipework which I use as headers, I then step them down to 40mm, both these are drain pipe and fittings are designed for gravity flow so don’t have the solid traps you are questioning.
All of this pipework is under ground and the AP area is on a slope and when the 40mm pipe arrives at the beds I’ve stepped down to a 25mm pressure pipe tee and the vertical goes to the bed via a 25mm valve and the other goes straight to another valve and is used for flushing the pipework when solids build. Most solids end up on the bed and although when I flush some solids do come out there aren’t as much as I’d expect and this because of how it gets stepped down with the velocity increasing and the head height.
If it is gravity fed to the beds then many will use an unglued elbow on the end of the pipework at the bed and adjust the flow by twisting the elbow or raising or lowering the outlet which is effectively raising or lowering the head of water.
I think that made sense. :think:
Hope this helps,
Merry Xmas.

Author:  Los Angeles Will [ Dec 27th, '20, 10:55 ]
Post subject:  Re: SLO Design Questions

I know what you mean about someone else taking care of the fish Rcmaveric!

My daughter asked me the other day, if she should feed the fish. I told her not to worry about it, that they can go a few days without eating. I ended up going to check on them later.

There was enough food floating in the sump to feed about 20 fish, and there are only 2 in there, and they aren't very hungry because it's cold.

I know what you mean about having a dream system too! I also have my dreams, and some big ones at that,
but I am lucky to have what I do, for now.

It makes sense that a larger pipe would help with the gravity flow to the beds.

For the plumbing from the pump, I also would likely use 3/4. I'm using it right now, but I'd just use a longer piece to get to the tanks. It's poly pipe, so it won't need many elbows except for where it splits to the tanks, it will kind of naturally curve, and I have experimented with heating it which lets you shape it a bit .

Skeg, Using the unglued fitting to control flow to the beds is a great idea, and just what I was looking for.

One issue that I noticed is that the 3 in (76MM) drain pipe that I have doesn't fit tightly into a 3 inch uniseal. Fortunately, they have bells on one end for connecting to another piece, and this flared bell seems to fit snug enough to make a good seal.

Thank you guys,
and Merry Xmas!

Author:  Rcmaveric [ Dec 27th, '20, 12:48 ]
Post subject:  Re: SLO Design Questions

Have you looked into solar heating? There is a you tube videos of home made ones that are just black panels with tubing wrapped around it and placed in the sun. Appeared to work well.

I chose blue gill so I wouldn't have to heat the tank. As long as they don't freeze solid or boil they should be fine. Gold fish and minnows are the same way.

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