New to aquaponics

[MOTHERWELLFISH]

Hi everyone

I am new to aquaponics and live in cold Melbourne. I have setup a 1500 litre tank with growbed above with mixture of herbs and veggies 21 days ago. Put 20 x 20cm rainbow trout in 18 days ago (smallest the suppliers have down south this time of year)

Have been only lightly feeding the fish every 3 days, added bottled bacteria to growbeds from an aquarium at commencement to speed things up as water temp only 12 degrees C.

Ammonia showed up after 4 days and peaked at 4.00ppm before I did a 30% water change.

Ammonia has hovered around 3.5ppm for past few days and Nitrites showed up 5 days ago.

Took a reading of Nitrites this morning of 2.00ppm so did another 30% water change and are considering adding pool salts. Nitrates are showing 5.00ppm so looks like Nitrospira are coming to the party.

Concerned about the salts being absorbed by veggies. Some sites say to only do water change and add salt if Nitrites reach 10ppm, others say do it if goes over 1.00ppm?

Do I just wait and see since I am getting Nitrate readings now or should I be taking action now?

Fish seem to be fine, not hovering on surface, not being skittish, not just sitting on the bottom. Get very active when I approach and they "think" they are going to get a feed, poor ******s!

Feedback appreciated.

Cheers

Simon

[Rob]

Hi everyone

I am new to aquaponics and live in cold Melbourne. I have setup a 1500 litre tank with growbed above with mixture of herbs and veggies 21 days ago. Put 20 x 20cm rainbow trout in 18 days ago (smallest the suppliers have down south this time of year)

Have been only lightly feeding the fish every 3 days, added bottled bacteria to growbeds from an aquarium at commencement to speed things up as water temp only 12 degrees C.

Ammonia showed up after 4 days and peaked at 4.00ppm before I did a 30% water change.

Ammonia has hovered around 3.5ppm for past few days and Nitrites showed up 5 days ago.

Took a reading of Nitrites this morning of 2.00ppm so did another 30% water change and are considering adding pool salts. Nitrates are showing 5.00ppm so looks like Nitrospira are coming to the party.

Concerned about the salts being absorbed by veggies. Some sites say to only do water change and add salt if Nitrites reach 10ppm, others say do it if goes over 1.00ppm?

Do I just wait and see since I am getting Nitrate readings now or should I be taking action now?

Fish seem to be fine, not hovering on surface, not being skittish, not just sitting on the bottom. Get very active when I approach and they "think" they are going to get a feed, poor ******s!

Feedback appreciated.

Cheers

Simon

Hi Simon,

I'm still relatively new, but from advice given to me and my short experience:

1. How large is your grow bed? If you only have one, you may need more to adequately filter for that many fish, or add a biofilter.

2. Yabbies posted an ammonia toxicity chart based on water temp and PH - http://www.aquaponics.net.au/forum/s...9&postcount=19 - you didn't list your PH so not sure where you're placed in that.

3. Salting to 1ppt (so about 1.5kg for your system) is tolerated by all veggies from what i understand. I run my system at that constantly, as do many others.

Yabbies, Rupert, and many others will have great advice no doubt too.

Rob

[Yabbies4me]

Hi Simon, welcome to the forum!

Stop feeding, or adding any Seasol or other additives. It sounds like the system is cycling nicely, so if your fish aren't showing any signs of stressing maybe hold off on the water changes, unless the Amm, or Nitrites rise further, then maybe another 30% change with water that has been aired for 24hrs.

I don't know what site said don't salt until Nitrites reach 10ppm... salt wouldn't be required at that level IMO... because you probably wouldn't have any fish left.

Your Amm is also high, but Melbourne's cold temps are probably your saving grace in that respect, refer to the chart Rob posted the link to above... What is your pH sitting at?... I suspect that might also be within a good range, that would help with high Amm levels as well.

I would definitely add some sea salt to mitigate the Nitrites, about 1ppt-2ppt. Most plants will be fine with salt to 3ppt (3kg per 1000L). Strawberries will be the first to look crook, from as little as 1ppt. Beans and some others may start to get some leaf burn around the 3ppt mark, but you don't need to salt to more than 2ppt for Nitrites.

Also, as Rob has asked, how much gravel capacity do you have in your GB?... for 20 fish you should have at least 500L of gravel IMO, preferably 600L. 25-30L of gravel per fish is a safe ratio. That's provided the beds are 300mm deep, or more, if the beds are shallower you may need even more gravel capacity, because of the 50mm or so of dry gravel on the surface that doesn't contain beneficials.

Good luck, keep us informed.
.

[Murray]

Yes to all the above, but add more gravel grow beds asap or some additional filtration. Trout like really clean water. Once you start putting the feed back in the filtration will become very important.

[MOTHERWELLFISH]

Thanks for everyone's quick responses and the helpful chart. pH is 7.8 so Ammonia level would be an issue if it continued.

Tested just at lunchtime, and after this morning's water dump, the Nitrite is now 0.50ppm and the Ammonia is 2.0ppm.

Interestingly the Nitrate level has stayed at 5.0ppm.

I have added some salt as added insurance.

Growbed is about 550 litres. I'll look into adding another one but space is an issue.....

Cheers

Simon

[Murray]

Check your Nitrate test, if not done exactly according to directions false readings can be obtained. Are you using a Freshwater Test Kit?

[MOTHERWELLFISH]

Yes, using freshwater kit, filling test tube to marked line, 10 drops of Nitrate tester 1 and 10 drops of Nitrate tester 2, shake, wait 5 mins, check against chart.

[RupertofOZ]

pH is 7.8 so Ammonia level would be an issue if it continued.

Tested just at lunchtime, and after this morning's water dump, the Nitrite is now 0.50ppm and the Ammonia is 2.0ppm.

Interestingly the Nitrate level has stayed at 5.0ppm.

I have added some salt as added insurance.

Growbed is about 550 litres. I'll look into adding another one but space is an issue.....

As members have noted above.... and I'm glad you have added some salt... 1ppt is sufficient to mitigate against nitrites...

Have no idea who... wrongly... suggested waiting until nitrites rose to 10 before action is required.... as, particularly with trout... nitrites are probably more of a concern than your ammonia reading....

You have reduced your ammonia, and nitrite readings.. by successive water changes... but you're also probably lengthening your cycling time by doing so...

Certainly salting to mitigate against the nitrites was required... I hope you resalted back to 1ppt after any water change...

And exchanging water has brought your ammonia levels back to within tolerances.. barely... in relation to the chart that Yabbies reposted...

But your levels are still high.... as is the fish biomass... for a new "cycling" system....

Your nitrate reading of 5.. is probably correct... but represents a transitory nitrification by Nitrobacter.... your nitrospira... which are totally inhibited by the presence of ammonia... will not kick in until the ammonia has dissapated... hence you're unlikely to see any rise in nitrates until it does...

When the ammonia falls.... the nitrospira will rapidly multiply... and nitrites will begin to fall quickly.... while nitrates levels will explode exponentially...

Water changes, and temperature... will only delay the process...

You are, although I'm loath to suggest it.... better off, if cycling with fish.... to adjust your ammonia tolerances... and mitigate against nitrites as well... (salting still advisable)....

By adjusting your pH slightly... with Hydrochloric acid.... to bring the ammonia toxicity and pH relationship back to acceptable levels...

The Hydrochloric acid... and it's the reason why Hydrochloric acid is preferred over and above any other acids/pH down products.... dissasociates into chloride ions.... with the chloride ion being the mechanism that mitigates/regulates the blood osmotic balances that mitigates against nitrite poisoning...

So.. stop feeding... stop water exchanging... keep your salt level to 1ppt... and if need be, i.e if your ammonia tolerance is marginal... adjust your pH accordingly....

Your nitrate levels are unlikely to change until the ammonia disspears completely.... and aren't of any concern...

Even when your levels indicate that you may be "cycled".... your system will still only be cycled to a "base" level... and beginning to feed will undoubtedly see short term ammonia/nitrite spikes...

You will have to adjust your feeding accordingly...

This poses a bit of a problem... as your system is stocked to effectively a maximum... for a new system... whereas your nitrification is basically at a minimum level....

And you need to get the feed into the trout to promtoe growth before spring/summer temperatures rise too high...

As Murray and others have noted... and in relation to the above... I really think you need to add another 500L of grow bed... immadiately... or at the very least... sooner, rather than later.... to ease the pressure on your system/nitrification
.

[MOTHERWELLFISH]

Rupert

Thank you for your very detailed response, very much appreciated.

System cycled on Sunday but as you have advised I have been keeping a close eye on the ammonia and nitrite levels since I have resumed small feeds in the morning in late arvo to enable adjusting for spikes.

Nitrites and Ammonia have been staying at 0.25ppm for now and plants are really taking off, see attached picture. Can't wait until snow peas and climbing beans cover the wire trellis above.

Cheers

Simon

Pictures 09.09.2012 002.jpg

[tpilk]

One other small bit of advice - stay out of the aquarium shops for your AP needs. Bottled bacteria and for the most part, water changes have no place in AP. Tropical fish raising is a completely different animal and I say that after enjoying that hobby for over 30 years.