Backyard Aquaponics
A place to discuss aquaponics

Fish Tank: 1500L
Fish: 4 tilapia
GB1-560L, gravel top up with hydroclays, flood & drain
GB2,3 - 560L, float raft

2011.08.30 Fishless cycling
2011.09.04 Add 4 tilapia (two 8cm, one 12cm, and one 15cm)
2011.09.06 Start planting some vegies

Water test:

2011.08.31 PH=8.0, NO2=0, NO3<5, NH3/NH4=0
2011.09.05 PH=8.0, NO2<0.25, NO3=5, NH3/NH4<0.25
2011.09.06 PH=8.0, NO2=0.25, NO3=5, NH3/NH4<0.25
2011.09.09 PH=8.0, NO2=0.5, NO3=5, NH3/NH4=0

Can someone advise if the reading for NH3/NH4 is normal as which increased only for a short period and became 0. Can I add more fishes in now or should I wait until NO2 has decreased to 0? and do I need to deal with the PH now? Thanks.

cty

IMHO the nitrogen cycle is not established, and .25 to .5 nitrites in 3 days is very dangerous for the fishes.

hi Natmaka,

Thanks. I understand the complete nitrogen cycle is not established, can I assume it's half way established as it seems there are already bacteria converting the ammonia into nitrites. With nitrities of 0.5 now, fishes appears to be ok and there is no signs of uncomfortableness. Just hope the NO2 level will decrease soon.

ty

Hi cty. You can assume that the bacteria that convert from ammonia to nitrite are present and also those that convert nitrite to nitrate. It looks like the bacterial conversion of nitrite to nitrate is not keeping up yet. Not time to add more fish yet because of the nitrite levels. Even when the nitrite dissappears you should proceed with caution because it's easy to overload a system at this stage.

I thought that fish tank looked bigger than 1500L.

Yeah as suggested, hold of for a little while yet, with the high pH take things slowly especially your feeding..

Hi cty

I haven't seen those particular floating rafts you are using before. You wouldn't happen to know the brand or manufacturer by any chance?

Thanks

hi Scotty, thanks for the advice. will keep an eye on the nitrite level. no fish will be added before it drops to zero for a while.

hi Earthbound, yes it's 1500L (200Lx100Wx75H) but you are right that it looks bigger because there is a lip of 8 cm on every side of the edge. PH has been staying at 8.0 from the beginning. Am thinking to add some lemon juice, do you think it's advisable?

hi furnaceboy, you mean the dark green one right. the manufacturer is in Taiwan and they said it's patented. as shown in the attached pics, each panel has 8 holes. with the cup it's convenient for planting the seedlings. will pm you their website (in chinese though) for your ref.

Furnaceboy, you can get a similar product here in OZ on eBay... it was dubbed the "ufo"...

http://www.ebay.com.au/itm/Floating-Pla ... 5ada89359f

The above could be a copycat... or it could be a new product from the original maker...

Rupert, i think it's from the same maker as I can see it also in their web. ufo one can be combined to fit different sizes and shapes.

As for adjusting the pH, you might want to figure out why the pH is high before you take any action.
Is the high pH because of your source water? (need to air out the water after drawing it from the pipes before doing the pH test since trapped carbon dioxide will give you false low pH readings from tap water.)
or
Is it because of your media? (put a hand full of your gravel in a cup of vinegar and see if it fizzes or not)

If it is your media, then adding acid to your system will only cause more problems than it solves.
If it is your source water. I would recommend adjusting the pH of the top up water before using it in the system so you can do it in a safe controlled manner and use the adjusted top up water to slowly bring your system pH down.

Now if it is simply because it's a new system and not cycled up yet, you might not need to do much and the pH could come down on it's own as the bacteria use up the buffers in the water.

hi TC, thanks for the explanation and advice. The PH of the tap water here is around 7.6~7.8 tested overnight so the increase must be from the media. I collected the "river stone" near the seashore which contains crumblings of seashells and I think this is the cause. If PH8 is not an immediate threat to either the fishes or the vegies I will leave it as it is for now as you have suggested. Meanwhile I am looking at the possibility of rearranging the drainage pipe of the rainshade to enable the collection of rainwater for top up purpose later. Thanks again.

An update of the water test:

2011.08.31 PH=8.0, NO2=0, NO3<5, NH3/NH4=0
2011.09.05 PH=8.0, NO2<0.25, NO3=5, NH3/NH4<0.25
2011.09.06 PH=8.0, NO2=0.25, NO3=5, NH3/NH4<0.25
2011.09.09 PH=8.0, NO2=0.5, NO3=5, NH3/NH4=0
2011.09.12 PH=8.0, NO2=0.5, NO3=10, NH3/NH4=0
2011.09.14 PH=8.0, NO2=0.25, NO3=10~20, NH3/NH4=0
2011.09.15 PH=8.0, NO2=0, NO3=10~20, NH3/NH4=0

I think the above has confirmed that my system is cycled. Am surprised that it only took 16 days to cycle the system. I believe the hot temp and the use of a piece of a filter blanket from an existing pond has speeded up the process. Am arranging to add in more fishes and vegies and expecting a full-blown of the plant soon. cheers.

cty

A couple of pics to show the plants now. A lot of the seeds on the raft bed are yet to germinate.

Getting through the initial spike of cycling up in under 3 weeks is not uncommon. Please keep in mind that you are really only just through the initial cycle up. Your system will need to work up to each increase you make in fish load so every time you make a change, keep a close eye on your water tests and adjust feed accordingly to keep from having any major spikes. It is this first few months of system operation where the system is getting it's balance and you are learning how it will react to different things that you have to keep the closest eye on water tests.

hi TC, Thanks a lot. Will continue to monitor the water test as per your advice. Am thinking to add some koi to mix with the existing 4 tilapia but the fish farm says currently it is out of stock. Hope I don't have to wait for too long as oherwise the nutrient will run short for the plants.