Backyard Aquaponics
A place to discuss aquaponics

Hello everyone!

I constructed my first system and started cycling today.

It is a small system made of fish tank 500l/132 gal, holding around 400l of water, a filter made from old plastic barrel, sump tank of around 300l / 80 gal and 2 old bathtubs both cca 250 l / 66 gal for the grow beds.

The beds are on my terrace and everything else below so that the plants get a lot of sunlight and fishe stay in the shade. It gets to 35 C / 95 F during the summer months. I filled the bathtubs with expanded clay (each bathtub cca 150l of expanded clay.)

I use a 10000l/h - 155W submersible pump - LINK

As I said I started cycling today with urea, added a tea spoon and leave it to mix well.

Later when I tested the ammonia levels were at 0,25.

Ph is at 8,2. The water was at first 7,5 so I guess it is the expandable clay that is increasing ph.

I have by hand some 100% natural seaweed fertilizer, which I might add to the mix and plant first plants soon.

I also have some natural hydroponics fertilizer, do you think it is save to add it? LINK

I am attaching some photos as well. Sorry for the bad quality

Hi Guljo, welcome to the forum

Urea has to break down so it may take a bit of time for the ammonia levels to go up - I wouldn't add anymore of this or the hydroponics fertilizer yet (you might push the ammonia levels too high).

Hey, thanks for the welcome.

I checked again today.

Ammonia is unchanged at 0,25

Ph is at 8,4

How long it takes for urea to break down?

Should I be worried about ph levels?

Lots of variables determine how long it takes. High or low pH, high or low temp, bacteria and probably others I haven't listed. The shortest I've seen is about 2 days and some methods with peeponics call for aging for over a month. The long aging time has to do with raising the pH enough to kill off any e. coli (I'm not actually sure this would work but urine is normally sterile). In this aging process as the ammonia is formed the pH rises.

You'll have to be patient because at some point you'll see the ammonia spike .

Ok, so patience isnt one of my virtues

I added 2 more tea spoons of urea on 9th April, 4 days ago.

Until yesterday nothing has changed, and ammonia levels were at 0,25.
I tested nitrites as well and it showed something like 0,25 not sure where this come from. Is it possible that the process started already?


I also decided to add my plants and added a cup of liquid seaweed and 2 dcl of Hydro-SuperMix to give my plants a good start.

The ph is unchanged at 8,6

Today the plants are looking good.


But the water testing was a shock, ammonia levels are skyrocketing Looks like they are around 8ppm.
I guess that the urea reacted to liquid seaweed or Hydro-SuperMixMy
My plan is to run the system and wait. I have no plan of adding fish sooner than in one month.
Ah and the nitrates levels at at zero.

Well, the webpage for Hydro-SuperMix says it contains ammonia, nitrite, and nitrate. It's designed for use in hydroponics, not aquaponics, so it's probably stronger than anything that would normally be used with fish. And your seaweed fertiliser probably has assorted nitrogen compounds in it. And there's also the urea, which has been quietly aging into ammonia... It's a good thing you don't have fish yet! You've got way more than 8ppm of ammonia there, it's very dark and you can see that it's more blue than green.

I did the same thing recently, don't feel too bad! It's really easy to get impatient and add a lot when a little doesn't seem to be getting results. Don't put any more stuff in! Just wait and keep testing, you'll see the levels change as it cycles.

Almost one month has passed and the system is cycling well.

The results of today testings are:

Amonia: 0,5
Nitrite: 5+
Nitrate: cca 110
Ph: 8,4
Water temperature 15 Celsius

Is now the time to add fish? Or should I wait some more?

The salads are doing great.

Dober Dan Guljo. I'm just back from a short holiday in your fantastic country. Wish I'd had a bit longer.

At your relatively high pH of 8.4, your ammonia level is likely to be toxic at water temperatures of 8 C and above. http://www.backyardaquaponics.com/infor ... nd-charts/ And the nitrates are still too high as well.

Wait till the nitrites and ammonia have dropped right down... ammonia in the safe range according to the linked chart and nitrites ideally zero. Then you can add fish.

You could consider adding some hydrochloric acid to your water... bringing the pH down means traces of ammonia are less toxic (less free ammonia in the water) and also you're less likely to get iron deficiency. There are heaps of threads on this forum about adding acid so I'll only say you should do it slowly and add your acid to some of your top up water and test it before you add it to your fish tank.

Good luck.

Dober dan Dave! It is great to hear that you liked it here, where have you been?

I read that the ph will drop down by biological activity in the system. Mostly caused by the bacteria.

There has already been a small drop from 8,6 to 8,4.

Should I start adjusting ph already or maybe wait a for a bit more to see if it will drop naturally.

I only had time for a few nights in Ljubi and a day trip to Lake Bled, the nearby caves and a couple of castles... the sightseeing is lovely but I was really impressed by how friendly and apparently happy everyone was and your food and wine is great. I'm keen to get back one day.

You're right about the pH dropping naturally. I believe it's because the nitrification process produces nitric acid. Some people report that it happens quickly but it took my system about 6 months before I had to stop adding acid.

I probably spent (still spend) too much time trying to adjust my pH - the wise people on this forum generally advise people to relax a bit about it. There's a wide range of pH that works in aquaponics... you'll find various posts on this forum about exactly what's ideal. But I think most people run in the range between about 7.5 and 6. So, if your pH is dropping already, just sit back and watch.

But have a good look at that chart I linked... so you can see how the pH and temperature impact on the toxicity of the total ammonia - which is what you're probably measuring with whatever test kit you have.

Wow it is surprising you got the impression everyone is happy, if you would stay longer I guess you would change your mind. Perhaps you were just lucky to meet the right people

Chart is noted and bookmarked.

Today I did another test and it looks good

Amonia: 0,2
Nitrite: 5+
Nitrate: cca 120
Ph: 8,3
Water temperature 15 Celsius

So Amonia is almost gone, Ph dropped for 0,1 and Nitrates are still rising.

I directly sowed some seeds of cucumber for pickling, some gourds and ecinacea. They are sprouting now and will help to consume all those nitrates.

Something interesting is happening to my system.

I did a test today and the results are a surprise to me:

Ammonia: 0,2
Nitrite: 0
Nitrate: 0
Ph: 8,3
Water temperature 11 Celsius

In just one week all nitrites and nitrates are gone, but ammonia is still at 0,2. Is it possible that my greens consumed it all so fast?

Should I add some more ammonia to test the bio filter or just add fish?

I decided to test the bio filter, so I added a tea spoon of UREA (I crushed it to dust) yesterday.

Today I measured the water:

Ammonia: 0,2
Nitrite: 4
Nitrate: 20
Ph: 8,2
Water temperature 13 Celsius

Looks like Nitrosomonas sp. is nicely colonized, but Nitrobacter sp. is still a bit slow. I hope Nitrites will be gone in 24 hours. I think that in this case it is the right time to add fish, correct me if I am wrong.

Happy to see the Ph falling

If your ammonia and nitrite are gone within 24 hours then you should be OK to add fish. Your water temps are low, your filter won't be working at it's best and you'll need to give the fish time to adjust if there are large differences (pH and temp mainly) between where they came from and you setup. What kind of fish are you going to get? The temp will also affect the feeding - Trout will still be eating but many fish won't eat much at this temp.

Because of your high pH, watch the ammonia levels carefully (especially if the water temp goes up) and if you are feeding ramp it up over a few days to give the filter time to adjust.

I will make another test first thing in the morning, I am not sure about UREA though it has the slow release of ammonia.

I will add carps, around 10 of them. Cca 10-15 cm, 100-200g. I have 400 litres in my FT and around 700L in total.

The temp will go up, we are in beginning of summer here, the ammonia will be more toxic but on the other hand filter will work better.