Aquaponics - Mould

I hate it when nature takes out the bad day it's having, by taking it out on me, and bringing me grief in the aquaponics system. What have I every done to nature?

Oh yeah...note to self - send "sorry"card to nature re: carbon footprint.

I don't mind so much when things go wrong that are my own fault. Sometimes I take shortcuts in the way I build stuff, so I feel that it's inevitable that it will need some "adjustment" at some stage in it's life.

But mould is a different story.

I mean it's still my fault, but I'd still rather it didn't happen because it's kind of icky.

When I built the new grow house, I didn't bother reinstalling the computer box cooling fan I had hanging from the top, to stir the air within the growhouse.

Opps.

So now I see mould on the PVC strawberry towers.







I have no idea how I'm really meant to spell those two words so this will have to do.

I've decided to spell mould, "mould", because when I made molds I used "mold" already, and I cant really see using "mould" for mold, and "mold" for mould would make that much difference anyway so I'll stick with "mold" for mold, and "mould" for mould.

I wouldn't want to confuse anyone.

It's also growing on the strawberry plants.

And that.

Nature.

Is unacceptable.







When my pH dropped too low, someone who knows stuff, told me they thought my leaves were showing a potassium deficiency. It turns out different minerals are available to the plants in varying degrees depending on how acidic the water is.

Sounds fair.

The solution is, you can adjust your pH by adding shell grit to your grow bed. Shells are made of calcium carbonate, and that raises your pH. The natural process of converting ammonia to nitrate via nitrite cases your system to become acidic over time, so the shell grit acts as a balance. It's convenient as well, because the more acidic your system gets, the more the shell grit gets dissolved. Once the system is no longer too acidic, the shell grit stops dissolving.

The system finds a balance.

In the meantime, as I was waiting for my system to gently come back to a pH of around 7, I added some potassium bicarbonate.

This adds potassium, which was a nice boost for my plants, but it also adjusts pH away from being too acid.

So I bought some Eco-RoseⓇ

It's actually sold as a solution to powdery mildew, and I guess that could be the culprit.


I dont actually know what powdery mildew looks like, and it would only take 5 seconds of my life to search for it, but that would take the mystery out of life.

Either way, the strawberries will enjoy it, so I'll give it a go.




Not just Aquaponics - Mould - 120 things in 20 years

Aquaponics - Fish waste solids masticator

I guess it's just plain laziness, but I'd rather not chew my fish's solid waste.

Luckily shell grit is willing to do it for me.

This is as yet untested, and in my experiments so far, there are some potential stumbling blocks to overcome, but this is what I'm working on...

We need shell grit in the system to buffer pH, so I figured I'd put it to use to break down solid fish waste, before it enters the grow bed. This is probably unnecessary, but I'm hoping to distribute the waste more evenly throughout the grow bed. I'm also hoping to grow some strawberries in PVC pipes at some stage, so it will be necessary to have very clear water running through them so they don't block, as the roots will almost fill the pipes.

This represents a possible solution to keeping the water moving freely throughout my system, if I end up needing it.

The general idea is that fish solids enter with the water, and because of the direction of the inlet flow, they swirl around. The water overflows leaving the solids behind. In aquaculture, and sometimes in very densely populated aquaponics systems, this is employed with a tap at the bottom to allow removal of the solids from time to time.. It's called a swirl filter or solids filter. All I'm thinking about doing is adding shell grit to one, and making the grit and the solids tumble around until the solids get small enough that they rise up and overflow in the grow bed with the water. I don't want to lose my solid waste because me plants want all the nutrition that's in it. The general idea is that it should be a prefilter, and double as a way to add calcium carbonate.

In my larger system, I think I will incorporate a solids remover in case something goes wrong and I need to instantly lessen the nutrient load. I wont need to empty it in normal use, but I will have the option in an emergency.

Aquaponics - Keeping good records

I had another fish death today, and it was after some rains. I had a niggling suspicion that the last one died after rains as well. There have been a lot of deaths and I now only have twelve.

I got some data from the bureau of meteorology to check against my records of fish deaths. Unfortunately, and foolishly I don't have complete records of deaths.

I had planned a good news aquaponics story today as the fish were all looking good, and feeding well over the last few days. I thought perhaps I'd put this fish death business behind me, so I figured I'd take some video to show how vigorous and healthy the fish seemed. I didn't notice the dead one. Not so vigorous.

Not recording those previous fish deaths was really crazy. My excuse at the time was that there was no point. It turns out keeping good records is incredibly important. If I had done so, I might now be certain of the cause of all my woes.

Here is a graph showing what I think is a correlation between my potential pH changing events, and my fish deaths. Fish don't like sudden changes in pH and a change can be fatal. Rain could have the effect of lowing pH, but I'm not sure if it could lower it, and then have it recover to normal levels before I did my pH tests. I'm also not certain if a short term change would distress the fish. After all, rain is pretty normal stuff in a fishy world.

B,D, and F all show strong correlations between rain and fish deaths. Rain would have a lowwer pH than my fish tank water.
A shows fish deaths in a dropping pH environment. Not due to rain, but due to the normal action of the nitrogen cycle. G shows the effects of the addition of shell grit to the system as a pH buffer to attempt (successfully) to buffer the system against sudden pH shocks.
C and E show significant rain events that may be responsible for my un-recorded fish deaths. Poor science I admit, but it was around these times that I lost fish, and I'm running out of other ideas. Did someone say "grasping at straws" ?

A,B,D, and F, all show potential pH lowering events. Sudden drops in pH can cause fish deaths. All my fish deaths I have on record strongly correlate to pH drops, or potential pH drops. Thats good enough for me to take action on.

I'll build a cover. It wont do any harm If I'm wrong.

On a lighter note, here is the happy fish video.

Aquaponics - pH buffering

In aquaponics, one issue that can effect your success rate is the pH of your water. pH is a measure of water's (or soil's or whatever's) level of acidity and alkalinity. A pH of 7.0 is considered neutral and also is what pure water measures.

Actually when we measure pH what we are really doing is comparing the relative quantities of two molecules. The hydrogen ion H+ gives us acidity, and the hydroxyl ion OH- gives us alkalinity.

The process of nitrification is acidifying, but in aquaponics we aim for roughly neutral water around the pH 7.0 mark. Depending on the media you use in your garden beds, your system's pH might not be close enough to 7.0 for your liking. Because the bacteria tend to make their world a little more acidic, the water will dissolve anything more alkaline than the current pH of the water. What this means is, if you have something like calcium carbonate, say in the form of shell grit* in your system, your clever system becomes self adjusting. Shell grit seems to have a pH of around 7.6. The more acidic your water gets, the more shell grit gets dissolved. This brings the system back into equilibrium. The shell grit will last for many years (depending on how much acid there is).

The shell grit is trying to get the water to pH 7.6, and the bacteria are forcing the water toward 6.0. Hopefully the result is your ph settles somewhere near 7.0 and everything gets along just fine. Plants also seem to enjoy a pH of 7.0, and that pH level also allows for the maximum availability of various trace elements to be liberated from the system and offered around to anything that wants them.

Shifting an aquaponics system toward acidity is a little harder. Most people add lemon juice, or vinegar. The test pictured to the left is the one at the top of the page but with 2 drops of lemon juice added. The problem with adding acid is that it would have to be done on a regular basis which is why we need to be careful not to use anything too alkaline as our grow bed media. Some people have gotten into trouble with limestone and marble.

Over the last few days I've been doing experiments with softwood charcoal, and have found it to steer a system toward being more acidic on an ongoing basis. The tests have only been going for a few weeks. The problem of a too alkaline system needs to be avoided from the outset, but if you have very alkaline water (say from a bore) charcoal might be a good way to pre-treat your top-up water and the initial water you use in your aquaponics system.



*shell grit is available for a few dollars a bag wherever you can buy chicken feed. Its made by crushing oyster shells or similar. Chickens eat it for the calcium they need to make egg shells.You can also use egg shells or snail shells for pH control in your system.

Aquaponics - Water testing

Its extremely important to make sure your water quality is within a desirable range. Aquaponics is remarkably stable and robust, but, for the first few weeks of setting up a new system it can require a little extra care. The best way to avoid any problems is to test your water every day until your system is mature and in balance or "cycled". (pictured here taking 30 days or so)

An aquaponics system is said to be cycled when it can process approximately 1 ppm of ammonia into nitrites and then process those nitrites into nitrates within 24 hours.

A decent freshwater test kit will enable you to get accurate test results for pH, ammonia, nitrites, and nitrates. It will set you back around 50 Australian dollars. They are widely available online or any good aquarium shop should sell them.

If you try aquaponics without water testing you will lose fish unless you are very lucky.

Add ammonia until you see a reading of 2ppm, then wait until your tests show ammonia is 0. Then add more and continue until your system can process 1ppm of ammonia and nitrites in 24 hours. Once you see readings of 0 ammonia and 0 nitrites you are cycled and can add fish.

Plants can be added on the day you first build your system but there wont be much for them to live on for a few days. My house water supply is rainwater and has some nitrates in it from normal environmental nutrient. Even normal tap water will have some nitrates in it so there will actually be something for small seedlings to live on.

Be careful to wash the soil from any store bought seedlings you transplant as they may have any number of additives that may be toxic to an aquaponics system. Growing directly in the grow beds from seeds is safest (and often quicker!)

Conduct water testing every day until you are cycled and then test every week or so or if ever anything strange occurs. Plants yellowing or dying can be a sign of something being wrong with your water chemistry and you might need to intervene in the early stages of your aquaponics system setup. More on correcting water problems later.

Always keep a record of your tests so that you can see emerging trends before they become an issue.

Aquaponics -Oops!

A few days ago I got some strawberry runners and, having no home for them, decided to make a small grow bed that would hang into the fish tank. When the main grow bed was flooded the water level in the fish tank would be below the new pot. When the main grow bed drained, the fish tank water level would be full to the top so the new grow bed would be flooded. No real problems there, in fact I felt a bit clever.

 I filled the pot with blue metal (road gravel in this part of the world) collected from my back yard. The day after I did this my pH went from 7.6 to 6. Now, I was told to expect a pH drop at this stage of fish-less cycling, and with the new gravel going in I thought it was within expectations.

The problem with pH readings of  7.6 or 6 is that they are at each end of the scale and as such it impossible to tell if they are actually beyond those levels. More on water testing aquaponics systems later.

Yesterday I discovered a white powdery substance near where I collected my gravel. I had a better look at it and discovered the gravel was dissolving! It was near where my flashing battery tail light for my mountain bike had rusted out so the conclusion I choose to leap to is battery acid!

I spent the afternoon washing out the system a few times, and now the pH is sitting at 6.8.

I was just a few days away from adding my fish so I guess its a good lesson to learn at this stage.