Category Archives: Water

Aquaponics Home System – Part 21: Water Test

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The aquaponics fish tank / aquarium is filled with tap water and has been degassing for a couple of days, and it’s time to measure the content of the water:

I’m using a Pondlab 200 water test kit from NT Labs which makes it possible to test 6 different parameters:

  1. Acidity (pH)
  2. General Hardness (GH)
  3. Alkalinity (KH)
  4. Nitrite (NO2)
  5. Nitrate (NO3)
  6. Ammonium (NH4)

The backside of the box shows what you have to do to make each test, along with color scales to find the correct value:

You’ll need to add one or more reagents for each test:

The test kit includes a log for your measurements and a very informative sheet explaining the background for testing each parameter:

(I’m not getting paid to promote this kit ;-) I just think it’s cool…)

I used a straw to fill each test tube with water directly from the aquarium and a kitchen timer to tell me when each test was done:

It’s actually easier to get a full cup of aquarium water and then go and sit down at the table instead of bending over the aquarium the whole time, so I’ll do that for the next tests. Some of the tests will take up to 10 minutes before the result is ready.

These are the results from my first measurements of degassed water, but without any fish in the water:

  • pH: 7.5
  • Ammonia: 0.1
  • Nitrite: 0.0
  • Nitrate: 0.0
  • KH: 3.5 °DH
  • GH: 5.0 °DH
  • Temperature: 23 °C (74 °F)

pH: We’re aiming at a pH value between 6.5 and 6.8 because of the type of fish and plants we selected already, so it seems that there’s a long way down from 7.5, and we’re not sure exactly how to lower this parameter.

Ammonia: This is good. Ammonia is toxic to the fish and must be oxidated into nitrite quickly by nitrosomonas bacteria. 1.0 would be alarming, and 5.0 would be dangerous.

Nitrite: Also good. If there haven’t been any ammonia in the water there won’t be any nitrite because it’s oxidated ammonia. A nitrite spike is expected when fish are added to the water, but the nitrite should soon be oxidated to nitrate by nitrobacter bacteria (or nitrospira?). 1.0 would be alarming, and 4.0 would be dangerous.

Nitrate: Also good. Nitrate is oxidated nitrite and since no nitrite was ever present there won’t be any nitrate in the water. If the level of nitrate goes up and keeps going up it’s because the plant tank is not doing its job of removing the nitrate from the water. The plants need to take up the nitrate through their roots (the N in N-P-K fertilizer).

KH and GH: Don’t ask (yet) ;-)

Temperature: A heating element has been dumped into the aquarium and set at 25 °C. It probably needs some time to get the temperature up.

We’re now ready to prepare the floats for the plant tank and add some bacteria.

Aquaponics Home System – Part 20: Suction Hose Filter

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The Eheim 1260 pump used in this system is quite powerful (65 watt) and the suction hose has just been dumped into the aquarium:

I was worried that the fish wouldn’t stay far enough away from the hose end and would get sucked into or onto the hose and get hurt. I decided to fit some kind of protection, and look what I found in the supermarket ;-) :

What a beauty. I’m not going to brew any tea with that one though. Half of it, and some steel wire will do the trick:

The sieve with steel wire is fastened to the hose with a cable binder:

And yes, I know what it looks like, but it’s the suction side, not the pressure side, remember? ;-)

Many rocks and stones have been added to the aquarium and small caves have been built, because the fish we want to have in this aquaponics system prefer to have places to hide:

The next thing I have to do is fix the lights, as some of the power cords were damaged due to being moved around all the time while setting up the aquarium.

Aquaponics Home System – Part 19: Mold and Tannin

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I don’t want to turn this blog into one about aquariums, but now that there’s an aquarium connected to the plant tank it’s part of the whole aquaponics system. Now that we have decided to use a normal hobby aquarium as fish tank we might as well spend some time making it look nice as a normal aquarium. If you’re not romantic at all you could just drop your aquaponics fish into a big black plastic basin – I don’t think the fish would mind.

We wanted to add some roots to the aquarium to try to recreate a real and natural looking environment, so we threw in a few pieces of wood that we found in the forest:

The problem is that the wood keeps floating since it’s not saturated with water:

The root to the right seems to be able to stay submerged. The other two are probably branches or stems.

The wood was left in the water in the aquarium for two weeks to allow it to absorb water to make it heavier so that it would sink to the bottom. What happened instead was this:

Nasty mold and what is probably tannin leaking into the water, changing the color of the water to light yellow:

Pretty nasty setup and delay before we’ll be able to add fish to the system.

The floating pieces of wood have been thrown out and the water has been changed. New roots from the pet store will be added together with stones to create the right look.

And now I’ll go open the door for the postman – he’s here with the water test equipment and nitrobacter :-D