Backyard Aquaponics
A place to discuss aquaponics

Here's my new SLO, basically a merger between my old SLO and what Scotty said to do. My SLO was originally 3" except near the bottom where I had a 3" to 4" coupling and 16" or so of 4" pvc. I can't explain why I did that, it made sense at the time to perforate a 4" piece rather than a 3" piece. Anyway, that's why you see it goes from 3" to 4" near the bottom. It probably isn't at all necessary, and is probably making my SLO not work as well as it could, but I didn't have another piece of 3" pvc to fix it now. At some point I'll probably make it 3" all the way to the bottom.

Like Scotty said, I took a big net pot for a bucket and a bucket lid and cut a hole in the bucket lid for the PVC. Before I screwed them together, I put a smaller net pot on the end of the PVC. Hopefully if any little fish make it past the first basket they won't make it past the second but will still be able to swim out of the big basket. I didn't use the atrium grate that Scotty mentioned because, although I had one, my dog mangled it I only had LONG stainless screws nearby, so I used what I had handy.

It's a lot less noisy than it was!

Thanks for posting the pictures.

Looks good Tori . I like shorter screws because of the fish, I was concerned they would get injured on the long ones like you have there but sometimes you have to go with what you have .

I came up with this scheme because I was heading on vacation and needed a bulletproof SLO. I'd been having problems with what I think is Cladophora algae slowing the flow into the SLO - nothing fatal but near HSMs. http://www.aquahobby.com/articles/e_freshwater_algae.php

Cheers

fantastic, so how's it working?

Hiya Tori nice work, well done. Does your ft water level raise much with that design when the pump is running?

It's has worked great for the better part of a year in my AP system . Hopefully Tori will find the same is true with hers. Since it has lots of extra surface area on the outer basket it's less likely to totally clog and the inner workings are the same so the water level shouldn't be affected.

My parents have a Walapini. Its basically a green house that is under ground. We used 2 rows of black barrels for heating. One row was filled with sand, the top row was filled with water. Half of the roof is plexi glass. It is based on solar heating. We have windows on two sides that we can open to cool it off. We started it last summer, we have been harvesting crops in raised beds since January. On a sunny day it can get up to 100 degrees or more, even in winter. I am going to build my aquaponics in there in the next month, hopefully.

That SLO looks like it would work quite well and it's a very good design, the only thing I could add is too try a lower net pot and see if you get a stronger current if the outlet was slightly closer to the bottom of the fish tank. Compare the two and I think you'll find the lower one would perform a little better but either way you have a very efficient SLO there.

I've found the uneaten fish food and solids tend to roll along the bottom of the tank especially further out from the SLO and I think if the current is drawn lower it helps the solids further out to get to the SLO, for example if the SLO outlet was 300mm off the bottom the current would drag very few solids up from the bottom of the tank if any and the bottom of the tank is where the solids are they're not half way up the tank.

I hope you Guys don't mind but the next SLO I build will be very similar to that design I think you have a winner there.



Skeggley it wont raise the water level unless you pump too fast, the same volume of water in and the same volume out, it's just an overflow and this case a very efficient one.

I'm going to put air line tubing over the screws next time I pull it out.

The water level does rise, but not as much as it did before and it doesn't make nearly as much noise.

The pipe is about 2" off of the bottom of the tank, I'm not sure how much closer it could be without impeding the flow. I don't know that you can tell from the picture. You can see the pipe in the big net pot, then a black band which is the inner net pot, then a white band which is the bottom of the solid pipe. (Actually there's another little 4" coupling on the end that the inner net pot is shoved over, but only because I needed another 2" height, it would have been fine without it if I had a long enough pipe.)

On mine, the end of the atrium grate sits on the outer net basket and that's all that separates it from the bottom. The pipe is free to slide all the way to the bottom so it's just a matter of cutting the pipe the right way in the first place. The flange of the atrium grate and the opening in the bucket lid keep the whole thing together until it's placed so you have to do a decent job of cutting and make sure the atrium grate flange is wider than the pipe. It also makes it so you can remove it as one unit and don't have to fish for parts.



I'm good with you or anyone else building a spin off or copy of this design and I'm glad you like it .

edit: Two possible improvements I considered based on some of the bottom drains I was seeing.

1. putting a bowl above the collar of the atrium grate but inside the large netpot (facing downward just above the bottom) to pull solids in better.

2. Adding an air ring right above the intake to create a flow in toward the pipe. A collander instead of a bowl might work better in this design since you want the air bubles going up in the center of the tank. An airlift inside the SLO might also get the job done.

Tori I see your pipe end sits down inside the net pot, I would try it as it is, see how it runs and then try pushing your pipe lower down into the net pot and see if that improves the current. You'll need to extend a piece of pipe above the "T" so it doesn't overflow at the "T" but you should be able too just push down without having too take the SLO out of the tank.

The closer to the bottom of the tank within reason is better and if you find that it is an improvement just replace your pipe with a longer one.


Scotty I think both your ideas are good a bowl inside the net pot with the SLO pipe down through it would work like a RFF dropping any solids that tended to drift upward back down into the flow again.


The air ring I think is also a good idea and I will work on designing a way of adding a fitting on the outside the pipe and pump air into that and have the air enter the pipe through small holes drilled around the pipe circumference. By not reducing the inside diameter with the air ring inside I think it would flow better.

I had an air stone in both the horizontal SLO's I had and because of the slots over the full length of the pipes it didn't do a lot, the air just built up on the inside top of the pipe and had more of a bubbling affect that restricted the flow of water, but I think your idea of an air ring at the base of the SLO rising straight up would work quite well.

This is so helpful. Thank you all so very much. Question, do we take the chance of breaking up the solids with an internal air lift? Joeblow, are you suggesting a combination of air ring and internal air lift? This all sounds intriguing? One last question; As you may know my FT has sloped sides and bottom, it there a benefit to plumbing the SLO vertically and not following the sloped sides?

If you have sloped sides, just put the SLO at the lowest point. It sould self clean.

Thanks Ron

Boss I'm close to finishing and testing a design but I've been held up by ordering the wrong size fittings from China and waiting 4 weeks to realise my mistake. Boss it wont have an air ring because I think that would cause problems, Scotty is thinking of using an air ring in his design and I will run my design past him when I draw it up, I am looking at using just an airlift I think an air ring would block flow if it sat on the bottom and restrict flow if it was up inside the pipe.

I think the physical size and shape of an air ring would block the flow and possibly even cause a build up of solids beneath it where ever you placed it.

I have all the components except for the air connection and as soon as I have a working model I will post the design and fittings on the forum.

As for breaking up the solids I don't think it would matter if it did, the main thing is they're leaving the fish tank and what you do after that is another thing again.

Boss I ordered 3 Stainless Steel 1/4" BSP male thread - 6mm barb fittings for China thinking that 1/4" would be the diameter and it's not, the diameter is 12mm so I've ordered 10 more 1/8" BSP thread and when they arrive I'm off and running. I could have used the 1/4" BSP with another right angle connection but it's not the way I want too go.

The China thing came about because here in Australia I could buy 1 fitting only interstate, I've forgotten the exact price it was but I think it was nearly $4 and then it had too be sent in an overnight bag at another $15.00, so it was $19 for 1 fitting.

The cost for 3 fittings delivered from China was $5.07 AUD and the 10 - 1/8" Stainless Steel 8mm Barb fittings cost $14.90 AUD delivered, still cheaper than the $15 overnight bag for 1 fitting.

I've ordered 9 extra fittings they will be used for a revamp of my air system, currently I have 18 - 6mm air lines running, most 2metres long and some 3metres long and I've noticed the air pumps are starting to get a bit noisy so I will run 25mm PVC pipe and tap threads for the 9 Stainless steel fittings.

That way it will shorten all the air lines and completely lose the 6 running from the back up compressor.

On plumbing the SLO vertically and not following the sloped sides, there would be less restriction on the flow vertically and less chance of any build up in the pipe and it would be a far better way too go.