Backyard Aquaponics
A place to discuss aquaponics

Hi people. I'm new to this forum.
Late last year (2011) I setup an aquaponics system in my back yard. Its a very small system at only 200Lt grow bed, 200Lt fish tank and 200lt water sump. I have twin aerators and electrically timed pumps that run for 15min/Hr. I have had 5 silver perch in my system since last November and they have grown considerably in that time. From the start the system had 350g of salt in it.

1 1/2 weeks ago I purchased 5 more fingerlings from a large supplier. I brought them home and balanced off the PH in the fingerling water before adding them to the main tank. Within 4 days the first fingerling was dead. After this initial death I noted the other fingerlings flashing, so I knew something was up. 2 Days later all the fingerlings were dead. Another 1 day later than that all my larger Silver Perch were sitting near the surface and sometimes flashing. I could see some whitish gel or slime in blobs on the scales of the fish. I measured Ammonium & Nitrite and both were at 0. I then added 500g of salt top my system.

1 more day on and I have lost 4/5 of my larger Silver Perch. The one left there seems to be sitting in his usual spot, but I have also seen him flashing infrequently.

Question/ Does anyone have any idea what the issue could be and where I should go to from here ?

Hi Nenexus, Welcome!

- When you balanced the pH of the fingerlings water, how far did you have to move the pH?... over what time period did you do it?
- What was your system water pH when you added the fish?... and in the days after?
- What was the max daily water temps in the days following the addition of the fish?
- Did you check the Amm and Nitrite levels in the days after adding the fish?... if so, what were the readings?

This is just my theory, but I believe you may have had an Ammonia and/or Nitrite spike after adding the extra fish. Fish gasping near the surface is a symptom of Ammonia poisoning.

You say your system has a 200L GB, however (and this is more of an issue with smaller systems), even if the GB was full to the brim and did actually have 200L of gravel in it, you’d probably find the volume of wet gravel, or “working” gravel (ie: gravel that can support beneficial bacteria), could be down around 150L, even less for shallower trays... 25-30L of gravel per fish is considered a safe stocking density in new systems, and possibly as low as 20L of gravel per fish in established systems, but that’s in larger systems that offer more stability in regards to water temp and pH. In smaller systems I recommend no lower than 25L of gravel per fish.

Let’s just say that your “working” gravel volume is 150L. Sticking to the 25L per fish ratio, your system could safely support a maximum of 6 fish… so your system was already running close to its maximum fish capacity. Then 1.5 weeks ago you doubled your fish numbers to 10, so 15L of gravel per fish, well under the 20L recommended for larger, well established systems.

You would’ve had an almost immediate spike in Ammonia, followed very closely by a spike in Nitrite… until such time as your bacteria colony increased sufficiently to be able to convert the excess Amm and Nitrite… this probably took quite a few days.

Add to this the fact that 1.5 weeks ago when you doubled your fish numbers… it was the hottest weekend we’ve had in months, I believe it got to 37º in some areas of Perth on the long weekend… a recipe for disaster, especially if your pH is high. There is a direct correlation between water temp and water pH that makes Amm more, or less toxic at different levels.

Just as an example, let’s say your water temp reached 24º on the long weekend (I know the water in my kids single blue barrel system did) and your water pH was say 7.8 (not uncommon in Perth)… you’d only need an Amm level of just over 0.5 for it to be toxic to your fish.

Even at a water temp of just 22º and a pH of 7.6... an Amm level of just 1.0 could start to become toxic.

It wouldn't unimaginable for your Amm levels to have reached 5.0 or even more for a short period after doubling the fish load in a system that was already stocked close to it's safe maximum. At that level in say 22º water... the water pH would only need to be as high as 7.0 for that amount of Amm to be toxic.

As it happens, I checked the Amm and Nitrite levels of a large AP system (2400L of GB/3000L FT from memory) on the long weekend, the person had just more than doubled the fish load in the system, The system was big enough (just) for the total amount of fish, but the bacteria colony was going to need a few days to catch up after he added the extra fish. The Amm reading was absolutely off the chart, I've never seen a test sample so dark green, it was almost black (see pic below)... His fish survived, but only because his system pH was 6.0 and his water temp was 19º... the Amm can be over 50.0 (yes 50.0) in that situation. He did some partial water changes over a few days and his bacteria colony caught up a few days later and his Amm dropped dramatically.

With Ammonia and Nitrite toxicity it doesn’t necessarily kill your fish at the time of the spike. It may not get high enough, or be toxic enough to kill them immediately, but it can do irreparable damage that slowly kills them, days or even weeks later.

Also, you mentioned that the system was salted initially with 350gm of salt, so not quite 1ppt. Unless you resalted occasionally, that salt would have been gone within a few months. The fish and plants will use the salt.

Cheers.

Thanks for the detailed response Mr Damage.

I did check the ammonia 1 & 2 days after the addition of the new fish. It all appeared at 0 at that time and I thought my system was handling the addition well. So at that point I didn't check it again until the fish started to die 3-4 days later. So as you say it is possible that there may have been a spike in ammonium and nitrite.

However, it doesn't explain the appearance of the dead fish.

Last night I added some Condies crystals (potassium permanganate) into the water as per another threads advice to someone else, who was getting fish deaths due to fungus. However my last fish was dead this morning.

All the fish had multiple semi transparent gooey white globs on them, including covering their eyes, and their scales looked a bit rough and patchy. So it appears that something else was also attacking them.

So what do I do now? Do I have to treat my tank in some way? or can I just go and add some more fish ? Whats the plan?

any pics of the fish? showing the damage?

Found this in a post from a few years ago... The diseases section might not help with your current situation (didn't find anything except for white spot that resembled what you're describing, but the pictures might help) but it's a good resource to have

http://www.dpi.nsw.gov.au/__data/assets ... Manual.pdf

A rapid pH change can cause the slime coat to fall away.

Stress can cause the fish to produce extra slime coat.

Infection or parasites can also cause the fish to produce extra slime coat.

If the fingerlings looked fine before you added them, then I would suggest they were. It's common for people to assume that they were sold infected fish if their fish die within a few days of adding them, especially if fish that have been in the system for a while, die after the addition of new fish. In reality it's very rarely the case that the new fish were infected... it's more an issue of water quality, normally due to:

- Overstocking
- Sudden increase in Amm that the system takes a few days to cope with
- Differences of pH and/or temp between the fingerling tank and the new tank
- Moving the pH too far, too quickly when trying to match waters

If there is a sizeable difference in pH between the fingerling water and main system water, it's best to peg the bag full of fingerlings to the side of the main tank so it's suspended in the water and can slowly take on the temp of the system water. Put an airstone in the bag, and initially remove about 20% of the water from the bag (discard this water), this is primarily to drop any Amm build in the bag. Replace the 20% with water from the system. Over a couple of hours gradually adjust the water in the bag by removing about 10% of the water (discard this water) every 10 mins or so and replace it with water from the main system. When adding the fish to the main system it's best not to put any of the water from the bag into the system.

I am very surprised that you didn't get any traces of Amm in your tests in the days following the addition of the new fish and doubling your stocking density... especially with 10 fish, five of which were mature, in a system with probably 150L of "working" gravel... I would've expected to see a trace at least.

Anyhow, for the system now, if you believe it's had infected fish in it, I would salt it too 6ppt and leave it at that level for a week or more, then do a 50% water change before adding the new fish...

...or treat the system a few times over a couple of days with your Condy's crystals, then salt the system to at least 1ppt before adding new fish.

I dunno... We've heard some horror stories about SOME fish suppliers.. Like one last week who was handed a bag and a net and told to help themselves, fish were dead in the tank and looking like dying in their bag, they lost them all within a few days.

Every situation is different of course but doesn't it seem strange that people who buy fingerling from Troutman never seem to have these problems that crop up so regularly with fish from a few of the other suppliers?

Yeh... there's one in particular, that is one of, if not the largest supplier of fingerlings to the public in the metro area, that used to get a mention frequently, with dead fish floating around in the display tanks etc, but I've heard they have picked up their game. I haven't heard any horror stories regarding them recently.


But as I said, if the fingerlings looked healthy when purchased, the odds are that they were. If you were at the fingerlings suppliers and you saw maybe one dead fish in amongst hundreds of otherwise healthy looking fish... that's life!... it happens, but if you saw even just 3 or 4 dead fish you wouldn't buy from them, well I wouldn't. You would also look for other signs, such as lethargic fish, fish hanging around near the surface, or near water inlets, or air supplies.

In the last few years being involved in the AP industry I've personally seen a number of instances where people have had fish die shortly after being added to a system. The vast majority of which seem to start noticing problems around the 3-5 day mark… and in almost every case it was those that:

- Were overstocked... many of whom had already been warned not to???
- Were putting fish in when the water parameters weren’t correct, especially temps.
- Had poorly designed systems.

Of those that I’ve been involved with that had well designed systems, were stocking the right fish at the right time, had erred on the side of caution when it came to stocking densities, had observed good practises when introducing the fish, and watched their water parameters diligently in the days and weeks after adding the fish… I don’t recall ever having one lose an entire batch of fish, maybe the odd one or two, but never the entire batch.


In my early AP days I managed to kill an entire batch of Trout bought from Troutman. Not with elevated Amm or Nitrate in the first few days, even though against the best advice of Rupe and a few others, I overstocked the system (most all of us do it when we first start out)… but gradually over a few months. It was due to suspended solids I suspect. My system pumped directly from my FT to my GB, so the pump chewed up the fish solids, releasing fines. Then the auto siphon drained the GB almost completely with every F&D cycle, so it dragged all the solids and settled fines from the floor of the GB and dumped them back in the FT with every siphon cycle. There was no ST which may have allowed for some settling… and no mechanical filtration… You live and you learn.

Also, I reckon the sort of person that orders from Troutman is probably more educated (from an AP point of view) because they’ve probably learnt of his existence through the forum. Being able to wait a couple of weeks for his delivery probably also means they are a more patient type of person that probably also thinks things through more carefully… as opposed to the impulsive type of person that smashes an AP system together on a weekend and must have fish NOW!... and who will then race out to the afore mentioned metro fingerling supplier and take whatever fingerlings are on offer when they get there… race them home and dump them in an un-cycled system… then not even monitor water parameters until something goes pear-shaped.

(None of the above is aimed at you personally Nenexus, these are just my general observations that relate to this discussion.)

Cheers.

So you've gone away from siphons.. towards a slow drain, timed overflow standpipe system then Yabbies...

And, no doubt...you certainly wouldn't be an advocate for the mincing CHOPII style of system either...

What's that shiny pointy thing sticking out of that prawn?

Nope!... Lurvs me siphons!... just make them differently now, so they leave at least an inch or so in the bottom of the GB with each drain cycle.

I hate the idea of continually stopping and starting pumps, especially when relying on a timer to do so.

I stop my pump manually every day when I feed the fish, once every now and then when I turn the power back on the pump doesn't restart, I give it a jiggle and in most instances it fires up, but every now and then it doesn't, usually when the bio-film etc has built up in and around the impellor... that's when I know it's time to give the pump a clean. If I was running a timed system my fish would've been dead a few times over from the pump not restarting... or I'd be having to clean my pump probably weekly as a preventative... too much hard work involved there!

I haven't had the need to set up a system in the CHOP2 configuration, or advocate the use of it... yet... but I can see it's merits in some instances.

The obvious drawback is the solids that may be returned directly to FT, but a customer of mine that set one up has killed two birds with one stone, he ran the returns from his GB's and the return from the pump all into a filter prior to returning to the FT... works a treat he reckons and the CHOP 2 configuration solved a design/location issue he had with his set-up.

...

Other than the blue barrel system, with loop siphons.... and my most recent system...

All my systems... and client systems... over the last 5+ years.... have all been timer based....

In that time... I've had one timer fail (after about 3 years outside).... 1 pump failure - blown capcitor (in 5 years)... and 2 client pump failure... (both 1-2 years of use)

Frankly I think the arguement about timer failures... and/or pump failures due to on/off switching... is bullshit...

I know you don't like timed F&D Yabbies.... but the "premise" you posted on PAP about timed F&D... is a nonsense...



So instead you've got a siphoned system.... it still takes 5 mins to fill the grow bed.... with no water returning at all during that time..

(As opposed to partial flow return in a timed system.. from the moment the flood begins... through the drain holes in the bottom of the standpipe... something you forgot to include in your calculations)

And then once full... a quick siphoned drain at full flow.... typically about 2 mins....

(This is about the norm... 8 F&D siphon periods per hour)

i.e....

8 x 5 min floods = 40 mins.... of no water return..... still water....

And

8 x 2 min siphoned drains = 16 mins of full flow...


Or to put it the other way.... a 16/44 cycle.... as opposed to the 15/45 cycle... you seem so intent on maligning....




As above... you've totally forgotten to account for the immediate return of water once the pump cycle starts in a timed F&D....

OK... it's not a "full" water return.... but it's still oxygenating....

Varying the timer period has benefits according to season... and/or... location...

But the rest... is pure nonsense...


And you can't say in any way.... that timed F&D doesn't perform at least as well as siphoned F&D... or even "constant flood"....

Indeed... in the trials done... I'd suggest that both "constant flood"... and "timed F&D".... did better initially than "siphoned F&D"....


And the forums are littered with people... having siphon problems.... haven't seen too many having "timer" ... or "standpipe"... problems...

'Yabbies' it sounds like you've been doing this for a long time.

Here's the pics that I promised. However, you 'll have to excuse the quality as they are black and white due to an incorrect camera setting at that time (new phone). I was going to take some more shots tonight, but the fish are now putrid...so I wasn't going there.

http://youtu.be/InWWdqk2Wlg

See what you all think. Its only a short video, containing 2 photos.

I have some more questions for you professionals/
- Where does the potassium permanganate go;
I take it its not building up with successive doses over the next few days ?

- Is it good practice to quarantine and treat new fingerlings with salt before they go into the tank?

- What level of salt should I maintain in the system, after all this is cleared up, and will it impact plant growth ?

- My system is only small as previously mentioned (150-200Lt GB, 200Lt FT, 200 Lt sump).
How much Seasol should I be putting in whilst I have no fish in the FT ? Seasol to maintain the bacteria
and keep the plants alive in the GB.

- I'm curious to find out which large fish supplier you's are all talking about...if its the same as
the one I went to ?

- Will Troutman supply the small qty that I would need (5-6 fish) ?

- Where does the potassium permanganate go;

It breaks down... basically leaving a potassium compound beneficial for plants...


I take it its not building up with successive doses over the next few days ?

No...

- Is it good practice to quarantine and treat new fingerlings with salt before they go into the tank?

Yes... preferably

- What level of salt should I maintain in the system, after all this is cleared up, and will it impact plant growth ?

It's not necessary to maintain a level of salt in the tank...

Although any treatment for parasites.. or fungal infections will require salting to between 3-6ppt...

You can just let this dissapate through (some) plant uptake... and by subsequent water top ups...

3ppt of salt will affect strawberries in particular... most other plants can handle up to 6ppt... for the life of any disease treatment....

Small/new seedlings can be impacted...

- My system is only small as previously mentioned (150-200Lt GB, 200Lt FT, 200 Lt sump).
How much Seasol should I be putting in whilst I have no fish in the FT ? Seasol to maintain the bacteria
and keep the plants alive in the GB.

A capful per week.... for the plants....

Seasol doesn't contain any useful amount of ammonia to feed your bacteria....

Your fish will produce all the feed for your bacteria


- Will Troutman supply the small qty that I would need (5-6 fish) ?[/quote]

I'm sure he could... and he will be at BYAP this weekend selling Silver Perch

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Huh... what's with the font sizing??