Backyard Aquaponics
A place to discuss aquaponics

Brian,

once the duckweed completely covers the surface of the water, then algae will not grow in the shade under it.................

Hi Brian,
I just looked back at the beginning and saw a bathtub system, is it still running and doing okay, or has it simply been superceded with the new project? Looking good!

Brian,

This last winter I kept trout in my swimming pool and fought to keep PH below 8.5. I also kept them in two other systems that dropped to 6.0 at most and have been buffered with Shell back to 6.4 or 6.8. The trout really did well in all systems, so I'd say don't worry about the PH on their behalf.

The plants will probably be happier with PH lower, but I did fine with 7.6 to 8.0 last summer....and some added chelated iron and potassium.

Concrete or lime is supposed to really push PH high for a while, but you say you have it coated. Aren't they coated with a concrete or lime plaster or was it something else? Folks who make concrete "live rocks" for aquariums seem to need to go through a lot of water changes to eliminate the excess PH (carbonate ions?), but after a while things stabilize. I think the concrete/plaster needs to lose the excess PH from it's surface or develop some sort of coating, but don't know details of the process.

Anyway, if it were my system I would complete the fishless cycling (NH3>NO3 lowers PH eventually), add trout, and keep adding some extra urea for the plants and for the PH.

Once again: that's a beautiful system you have built there.....


PS: hydrogen sulfide (rotten egg smell) should act as an acid as it oxidizes, so that is not raising your PH.

Some of the borewater in my area has the same smell, and on a memory I did a quick google. 1st link.
"According to the Environmental Protection Agency, a maximum acceptable level of H2S for fish and aquatic life is 0.002 ppm."
Plus a few others that indicate it could be an issue to the fish.

You may be safer to have a standby tank and gas off any buildup with a recirculating spray bar untill the smell is gone before using the water.
Others may be able to give more info.

Definitely don't want to throw fish into a system that was just filled with water overly rich in hydrogen sulfide. But as you are fishless cycling and the system is already full, unless you are still smelling that coming from the system, you are probably in good shape there. Small top ups should be fine, especially if the water is sprayed in such a fashion to also help dissipate gasses. Big water changes might be a different story and require time being bubbled before going in the system. (Gee that sounds so much like what we tell people about chlorine.)

However, don't dismiss the dangers of hydrogen sulfide!!!!!! If you allow large amounts of debris to build up in stagnant areas of a system and rot down in an anaerobic environment, you will be creating an environment that could easily put off huge amounts of hydrogen sulfide in quantities perfectly capable of killing fish. Gunk and debris building up in tanks is not a good thing. This is why settling tanks need the gunk sucked out regularly and if the gunk is stirred up and allowed to flow to other parts of the system, degassing towers or some other means to get rid of the hydrogen sulfide gas is a good idea.

This was the problem I had with my duckweed tank, leaves and debris tended to come in with the duckweed and settle to the bottom of that relatively still tank (duckweed likes still water.) Then anything that stirred up the bottom tended to give off the strong muck bottom smell. Luckily I only had some tilapia living in that tank and they seemed to survive just about anything but cold and domestic violence. So, I've come to the conclusion that duckweed tanks need to be protected from debris and some how fed ammonia rich water that is also somehow free of solids. Sigh.

Thank you all for all the kind words and advice and input. These first steps in cycling are trying and I appreciate all the help.

Faye, I used the bath tub systems guttering for hydroponic lettuce growing, it worked, but the algae growth and harsh conditions in the concrete surrounds where not favorable so I took it all down. NFT pipes must be closed! It was a good learning experience and the gutters will be installed elsewhere in a place for which they where designed... as gutters!

On the issue of hydrogen sulphide, I will get the rainwater tank going and use that to fill and top up the system from now on. It holds 5000 so it should be enough. The smell actually leaves the water quite quickly if it is left to stand for a couple of days.

Bad news on the Ph front. This evening it is 9.5! Must be the cement leeching into the water through the coating. I tested the Ph of the reservoir now which has a concrete uncoated floor and it's Ph is 9.5. It is now a year old. I hope it does not take years for the cement to stop affecting the Ph. It is all coated with several layers of the bitumen stuff so there should not be any contact with the cement Maybe the bitumen stuff is raising the Ph... Oh. Tcl the Ph of the well water stays at 8 from when it comes out and after a day airing out . Ammo is now 0 so that is good news though. I am going to dose it up to 2 again and see how long it takes to go down this time. Nitrates are off the chart. The water is now sparkling clear so algae threat has been eliminated It was actually getting a little green before the shade but now it has not even a tinge of color. Amazing how quickly it left the system. Filtered out I guess.

The pump seems to have slowed a bit. The strainer at the end of the pipe must be a bit blocked with debris. I will investigate tomorrow.

Plants seem to be doing fine and cabbage seedling are rocketing up although the lettuce needs shade.

Found the FT overflowing again this afternoon... another 15 degree swim. The filter mesh thingies I put over the slo where much too fine and had blocked up with small size gunk so I drilled them out with a 6mm drill bit all over. Hopefully this should be better otherwise I will modify them more. Not much good having a slo when the solids can't get through. This morning I thought OMG this thing is leaking like a sieve, but it must have just been the tank overflowing a bit all night. I probably lost about 500 liters.

I am working on an auto top up system using a toilet cistern thing that is all plastic. I will afix it to the pipe running into the sump at the low water mark so if it falls below that level it will fill from the rainwater tank.

This morning the Ph was back down to 8. Really confusing. I am going to take some more readings now and see where it is. What would cause Ph to go from 8 in the morning to 9.5 in the evening?

Ph still 8 this evening . Ammo down to 0.2. Have re-dosed it again.

Right- Ammo now 2.4. It WILL be close to 0 tomorrow at this time tomorrow! (wish-full thinking...)
I am thinking to employ the old 600 liter tank as a live food culture tank... put a glass top over it and get some daphnia eggs and such going. Backswimmers, beetles and wormy like creatures abound in the fish tank. When I took the mesh filters off the slo today there where plenty of creepy crawly things on it. I recon those trout are going to have a feast when they get introduced to their new home. I have also purchased a 220L plastic drum with a removable lid and gotten the O2 gas bottle filled in preparation for the fish mission.... All together now cycle cycle cycle cycle etc etc...

I don't know the details myself but I do know that using pure O2 has to be done carefully since there is some danger of super saturation that can be harmful to fish. Hopefully you can look up some instructions to make sure you don't cause danger to your fish in transport.

Hi Tcl. The trout merchant seems to know what is going on there. He said I must just make sure I had the regulator and that it was working properly with a pipe and an air-stone diffuser.

Cool just so you are getting some instructions from some one who know their stuff.

Did the ammonia get back down to 0 in 24 hours?

Oh, and on the topic of your SLO drain. How is that configured again? Is there any way you could easily modify it so you can pull out that section of pipe for cleaning and maint without having to go swimming?

In my tank, that is deep enough to make climbing in tricky and I don't want to climb in with lots of big catfish, I've made it so I can pull the parts of my SLO drain out and clean replace the grates without having to get in the tank.

No Tcl, sadly the SLO is all concreted in place. I guess one day I could make a stainless grate that is on a bar that attaches over the side wall in some way so it is easy to clean. I guess it need not be said but one really wishes one knew what one knows after building a system before one starts to build it. I would have done a lot differently. Perhaps I will scale the design up by a factor of two one day, but with 8 beds of the current size, and then I can do all the stuff I should have done on this one. That would be one serious system!

Ammo is now between 1.2 and 0.6 but still about 4 hours to go for 24 hours, but I don't think it will make it. It is cold today, don't know if that makes a difference, but I guess the water temps are about the same at around 15 degrees. Ph is unchanged at about 8.5. Sadly I am going into town this evening so won't be able to check later. I have also now used up all the pure ammonia. I have started to collect humonia now. How long does it take to convert to ammonia? I will try to find urea in town or more ammonia.

You really want the holes to be just small enough that you don't lose fish. Too small and they clog fast. I tend to either cut my pipe on an angle or cut crenelations in the end to create spaces solids can use but fish can't.

The holes at the bottom will get clogged at times. This is the second reason it is important to have a T at the top of the SLO: so water will flow into it rather than rising over the edge of the fishtank. (the first reason, of course, is to avoid creating an autosiphon and siphoning your whole fishtank down to growbed level. )



Humonia is a solution of urea. You can (and many do) add it very directly to your system. The two advantages TCL has found to aging are 1) it converts to ammonia so you can read your ammonia levels quickly, and 2) the ammonia or PH change or something kill all the E Coli (and, one hopes, other nasties). There is a whole thread: viewtopic.php?p=94324#p94324

So hydro, I cut the t's off below the rim of the tank? Well duh brian can't believe I didn't think of that. I could probably achieve a 15 min fill time with that arrangement. I take it the slow only needs to work in the first section of the pump time to flush out the solids... Thanks for that, I think you just saved me alot of trouble. I should have thought of the slits in the pipe thing too! would have saved me $8!

Trout arrive in Ph 5 water