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Backyard Medaka Microfarm Journal

modified lung

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It's getting warmer. Time to fix up the backyard recirculating system.

Last summer, for some dumb reason I moved the system into the sun and water temperatures hit a high of over 100°F. To make it worse, on the hottest day of the summer a raccoon, I'm guessing, ripped the wire out of the solar charger cutting off the pump and aerator and all my fish suffocated to death. All except one which I somehow found in a five gallon bucket next to the tank. How do these things happen?

My main goal then is to move the system back into the shade. And while I'm at it, why not reconfigure the whole thing. Why? Because I can. 

Currently the system consists of a 300 gallon circular tank, a combo settling/upflow mechanical filtration tank, and a 100 gallon stock tank as a sump.

On the to do list is (1) add the second 300 gallon tank I've had in the garage, (2) replace the 100 gal sump with a 55 gallon drum sump, (3) incorporate then100 gal stock tank some how, (4) possibly redo the filtration.

Here's some schematics I made for the new system layout:


Yes, I made this on Google Sheets. Yes, the Android version. Yes, with my six inch phone screen. Sure, it took way more time than if I used a real computer program. But I didn't want to wait that torturous three minutes for the laptop to boot up.

The schematic shows each 300 gallon tank having it's own filter both of which drain into the same sump. The 100 gallon stock tank would be connected to the two main tanks with two overflow syphons. This will give the tank some water exchange everytime the solar pump slows down or speeds up.


Here the combo settling/upflow filter design that I'm currently using:


It works better than most other filters I've used. And I'm not just saying that because I invented it. I rock. Every few months the filter media, a few large scraps of shade cloth, should to be taken out and hosed off. I say should because I don't. 

Instead I'd like a design that can be back-flushed with a few valves (shown as red lines on the schematics) which will make the filter much easier to clean out. 

Option 1: Upflow Filter


With this a heavier filter media like lava rock can be used which allows for a high pressure back-flush. The drawback here is if I don't back-flush the filter regularly, and I won't, then the holding tank will overflow. Overflow would be directed into the sump (not pictured) but there's a risk that surface dwelling organisms, like fish fry, could be swept into the sump in the process.

Option 2: Downflow Filter



1233757154_Screenshot_20220211-1945572.png.891b37b37b4aff001a4f7012af2206ce.pngAgain, a heavier filter media works here. With this design the inevitable neglect won't alter the flow path through the system like with the upflow design. Instead, water will just bypass the filter media before entering built in overflow and then the sump. The drawback is this kind of filter clogs faster. Also, the built in overflow and pipe that discharges water into the sump will both need to be capped during back-flush and that sounds like work.

DIY Bead Filter?

Here's something I haven't seen done before ...a DIY bead filter. But it's possible one of these could be made from basic plumbing parts.

The major advantages of bead filters are their filtration power, contact design, and they double as a biofilter.

The drawback is they require a pump to push water through. That means either unfiltered water will be go through the pump or another filter needs to be added before the pump and bead filter.

Double Chamber Design


This might be the best filtration method that exists today. I've seen these things filter out thick green water in a couple hours. 

The filter media is usually a bunch of air injected plastic beads. The beads are pushed against the top of the filter chamber by the pump's water pressure. To back-flush, the top chamber is drained and the flow of water is reverse through the bottom chamber where the beads are rinsed. It's easy ...too easy. 

Single Chamber Design

The single chamber version work in a similar way to the double chamber but can use Kaldnes style filter media. This clogs less often and is much cheaper than air injected beads.

Here's a schematic of a single chamber bead filter incorporated into a sump tank along with a few other unnecessarily elaborate features:


This is the direction I'm leaning. If I did this, the two filters in the original layout schematic would become basic settlement tanks or be removed all together. What do you people think?

Edited by modified lung
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  • 3 months later...

Flipped and filled the damaged tank with water this morning. Seems the repair was successful. We'll call this the "north tank". Then I leveled the cinder blocks for the "south tank".IMG_20220527_134802229_HDR.jpg.6a7ece34851ddcc4fb5eee050a706501.jpg

The 55 gal barrel will be partly buried and used as a sump. 


Here's the south tank right now which will be moved soon. I saw a fry in there this morning. Hopefully it's a whitecloud and not another koi x goldfish hybrid.

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Moved fish from the old tank into the north tank today. 


Goldfish. I thought there was only one in there. I'll probably give these away locally soon.


Three nice looking golden whitecloudsIMG_20220528_150340704_HDR.jpg.10310e6befa3b9c33d75136a7b77742a.jpg

Look at the color on this flag fishIMG_20220528_143957977_HDR.jpg.c705e0342b2c342a4190f459627f7401.jpg

A few neocardiniasIMG_20220528_152442868.jpg.390c280d1c7d36849d051f19c9f637f9.jpg

The koi got away before I could get a pic. Not sure if I'll keep him or not. He didn't seem to eat any of the goldfish fry and might be part of the reason the tanks aren't overrun with dragonfly larvae. I'll throw a few ricefish fry in there tomorrow and see what happens.

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  • 2 weeks later...

I want to keep most of this as simple and basic as possible. Here's a close look at the design for the drain:


You can also see the repair I did the the second tank 4 or 5 years ago. It's rubber coupler clamped over a load of plumbing glue. Not sure I'd recommend this but it worked.

The 1" threaded cap on the drain T will eventually be replaced with a valve. I always like the stand pipe, which sets the water level, to be on a 90° threaded street elbow. This is mostly because, if you glue on an elbow, the glue dries fast and it's almost immediately too hard to level the pipe vertically.

What I really mean by that is I screw up builds a lot. For example, you might notice in the picture above I glued on the drain T facing the wrong direction. Luckily I decided to flip the tank before the glue dried too much and noticed in time to still be able to rip it off with a big wrench.



Next I'll have the bury the sump a little so the tanks can drain into it. I also noticed the south tank is about 1" lower than the north tank. This is going to bother me so I'll have to bring some dirt back under the cinder blocks.

The good news is new location next to the garage is working so far. We've had a few +100°F days and the temperature in the north tank has only reached a max of 86°F. That's a lot better than 104°F in the old location.

Look at how bright these guys are. They'll look even better under the sun when this project is finally done: 468247071_IMG_20220611_1425390442.jpg.840e9d05a5e81ef5eec1f0023ed874d2.jpg


Edited by modified lung
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A little progress. Dug the sump hole ...then reevaluated my life decisions.PXL_20220617_182858972.jpg.4ebc3f71aef276c8a3ce9d84b0f9db19.jpg

My yard is full of buried stuff. Found a socket wrench, chess piece, and an old nickle this time.PXL_20220617_231500808.jpg.c83449688598e2851818591a351c470c.jpg

Glued in the south tank stand pipe and put the pump in the sump.PXL_20220617_204747094.jpg.392cc9640c3237464d6ef38a99746fba.jpg

Hooked up the new 100w solar panel. Eventually I'll mount this to the garage roof. PXL_20220617_232744920.jpg.f4e32f1a0996e179f3d227d0cb5a3019.jpg

I'll give more details on the solar setup when I mount everything to it's permanent location.

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  • 2 weeks later...
  • 4 weeks later...

Solar panel not mounted to the roof and no filtration yet but both tanks have been running for a few weeks. Miyuki medaka ricefish + some whiteclouds on the left and youkihi medakas, a koi, and 2 goldfish I'm still trying to give away on the right. Blackworms in the half barrel.


I might have a hundred miyuki fry already. This strain doesn't seem very interested in eating their young. Not as much as I am anyway.



No youkihi fry outside yet. Indoors they bred a lot more than the miyuki. I don't know if they eating their fry or just not breeding outside. Although I haven't found any youkihi eggs either. Could be they're afraid to breed with the koi and goldfish lurking down below.


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  • 2 weeks later...

I picked up eight tricolor Sansyoku Tomeirin medakas last weekend in the SF Bay Area. They are still juveniles but I've found a few eggs already. 


Surprise golden whitecloud fry. I though I had all males. 


I got hooked up with some free 55 gal barrels so now recirculating pond is turning into aquayard. 


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  • 3 weeks later...

Another 50 gal tank leak testing. I didn't want to drill this one so I added an external standpipe from the bottom. These probably won't stay here for the long term. I have 4 more of these 50 gallon tanks and eventually I want them to be on their own system.

Right now tri-colors are breeding in one 50 gal and the other will be for youkihi breeding. The youhikis eat their young in the large tanks while the miyukis don't.



I had some white 15 gallon barrels with the tops cut off laying around. Threw them in to hold fry. I'll have to screen the top ASP. There are dragonfly larvae lurking but they seem to prefer eating the scuds over the fry.


Onset continuous temperature logger.


Youkihis continue to get brighter orange in the sun.


Miyukis enjoying some flow


Edited by modified lung
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A few things I'm doing to prepare for the heat...

Blocking the sun from heating the surface water, especially in the 100 gal stock tank with the old solar air pump that jams every few days. The broad side of this tank is also facing the sun which isn't ideal.


The 300 gal tanks have water constantly recirculating so they don't heat up as much. Even so I hung some plant baskets to give more afternoon shade to the surface water in the north tank. I moved the cactus over more to block the sun as well. This tank gets full shade from the garage in late afternoon. The south tank goes into full shade much earlier so I'm not worried about that one.


I'm not too worried about the barrels either. There is already wood blocking the bottom halves and, even though the rest get full afternoon sun, they stay surprisingly cool.  When kept only half full the surface water isn't directly exposed to sun and the air in the top half stays a lot cooler. Then the ground is also a great heat sink all of which definitely helps keep the water cooler. I'm not sure we've had a 114°F day since I've had a barrel outside. I have a min/max thermometer in the white barrel which is the most exposed to the sun. So far the max temp has only been 88°F which is about 20°F under the hottest day this summer which surprised me.


Last, I covered any air tubes bent over the side of the tanks with a cut section of thick rubber tubing. I've had the transparent air tubing turn brown and melt on hot days in the past. I think from a combination of the sun and the tank rim heating up. So I made sure the air tube also isn't in direct contact with the tank at any point.PXL_20220905_173108435.jpg.f463eef605298380096d0a7adaaf4709.jpg

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Topped out at 93°F at the water surface so far. Ricefish eggs are hatching like crazy. I think the biggest risk now is the big mass of blackworms dieing off and fouling everything. Not sure of their maximum temperature tolerance but they all came out of the worm tower and are wiggling around on the bottom. The snail leeches are doing the same which is making it very easy to find and remove them. 3 more days until the heat wave is over.


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I love your tubs! It's amazing how things have come along this season. Very beautiful.

Uv rated split loom is great for protecting the tubing. You can get it pretty cheap, too. I use it everywhere outside.

And, I'm so ready for this heat to be over. It's 87 in my house. The walls are hot, we are in flex power usage, and it's just miserable.

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Heat wave day 3. Today's air temp high was 108°F. Better than yesterday's 116°F.

The half full barrels are working well. Despite getting full sun all day, the most exposed barrel today hit a max of 93°F at the water surface again while another mostly full barrel that gets afternoon shade hit a max of 105°F at the surface.

Still no fish deaths (koi, comet goldfish, ricefish, whiteclouds). Blackworms still alive ...I think. 

Another way I can cool the water is by draining the sump and refilling with much cooler water from the outdoor faucet. I'll do that a little later today. For next year I might try a USB fan that can plug into the solar controller and blow air across the water surface. Maybe that will keep it down a few degrees.

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