Unexpected Fish Deaths *** Help Please ***

[rdiaz63]

Hello everyone,

I'm new to aquaponics and I've been reading a lot since I was browsing the Internet and trip on this website about three month ago. After evaluating several systems posted by AHQ enthusiasts I decided to build my "Test System #1". I have some knowledge on Hydroponic so I constructed a system using PVC pipes. My idea is get used to the technology and learn from others problems and if everything goes find build a larger system later.

My aquaponics system consisting on a 15 GAL (56 Liters) plastic box as fish tank, a biological filter made of four PVC tubes about 4 inches in diameter filled with black gravel as I shown in the pictures. I cut about eigth holes in each PVC tubes to hold the cups for the plants. I filled the cups with vermiculite because it easy to obtain here in Puerto Rico. The fish tank is filled with 24 gold fish and the pump is a single 185 GPH submersible pump. The water is running up to the PVC tubes using and hybrid of flood and drain and NFT technique. Air is provided all the time using an aquarius pump via an air stone. The plants I chose for this experiment are several varieties of lettuce.

I've been experiencing fish death at least two per week since I bring up the system a couple of weeks ago and I honestly don't know what is happening. The water is Cristal clear and the chemical levels seems to be find. I'm providing good aeration and the water is running to the bio filter every 30 minutes. The fish looks very happy and eat every time I feed them (two times daily). The plants are growing very well.

Here I'm includes the reading since I start the system:


DATE___AMONNIA___NITRITES___NITRATES___PH___TDS(PPM)
8/16/08___0_________0____________10_________7.8______26
8/17/08___0_________0____________5__________7.8______107
8/23/08___0.10______5.0___________20_________7.8______137
8/28/08___0.10______0____________40__________7.8_______146
9/01/08___0_________0____________80_________7.8______161


I'm using a Nitrogen test kit used for salt water aquariums because the pet centers here does not carry fresh water test kit. I'm not sure if it can be use, but my readings are within the color code range provided on the cards.

Your help in this problem will be greatly a appreciated.

Regards

Robert

[Hamish]

Very neat looking system - well done.

A couple of things I can think of that might be causing issues.

1) If you didnt cycle the system to build up bacteria before adding the fish then the fish might have gone through the Nitrite spike your test results show. This could weaken the fish and stress them and they die later.

2) Perhaps contamination is killing the fish? Are there any local sources of contamination getting into the water? I once herd of a guy who had his fish tank under a clothes line and when it rained residue soap from the clothes on the line dripped into the tank and killed his fish. Perhaps the plastic tub is leaching something nasty? Local weed spraying?

3) If you can get a fresh water kit I would - perhaps order one via the internet? There must be a reason they sell 2 seperate kits one for fresh and one for salt - unless it is just marketing? Anyone know or have both kits so they can compare them?

How full are the PVC pipes with gravel?

[rdiaz63]

Hi Hamish,

Thank you very much for answering my post.

No I didn't cycle the system . I use the gold fish to produce the amonnia required to cycle it. That might be the cause of some killings, but so far, the system is stable (no amonnia neither nitrites) and the gold fish still dying. I lost 12 so far, about 1 or 2 daily. However, the plants are very happy.

Regarding the contamination, I cover the green house with clear plastic to avoid rain water enter to the system and overflow it. I don't know if the plastic itself can be the cause, so I'm gonna cover the fish tank and report what happens.

Today, I purchase a fresh water test kit and re-check my results. All the readings are the same except the PH that jumps to 8.0 from 7.8. I'm not sure if it is to high for the fish, what you think?

Robert

[Hamish]

Im not too sure on the pH for gold fish - a quick google search should turn up the answer but 8 does not seem too extream and a jump of .2 is not so huge as to cause stress.

What about temp swings? What is the temp of the water? Get a cheap max/min temp guage like this so you can see what the temp swings are from day to night. http://cgi.ebay.com.au/Digital-LCD-D...QQcmdZViewItem

Dont cover the fish tank tightly as it will stop airflow and cause a build up of toxic ammonia.

You did have a spike of Nitrite which could have stressed the fish enough for them to die days or weeks later - so your deaths may settle down.

Have a read of Jasons system here - he had a few issues starting up with a plastic tub of similar size.

http://www.aquaponicshq.com/forums/s...ght=countertop

Cheers,
Hamish

[nick]

you have to be careful with ammonia as the higher the pH the more toxic it is to the fish, below about 5.5pH ammonia is not toxic at even very high levels but at 8pH you are talking toxicity at even low levels. Have a google and you will find some info, but a quick search revealed this page
http://www.thekrib.com/Chemistry/ammonia-toxicity.html
that had some info on it,

Nick

[Jonathan Dyer]

G’Day, I grow goldfish and Koi.

I would say that the lack of cycling for your system is a concern and may be highly responsible for your fish deaths. In all the years I have kept my fish I haven’t lost one.

Secondly I would bring your pH levels down to 7 and try to keep it there. Goldfish like a bit of hardness in there water so if possible try to increase your levels to 300. Additionally, I would add one ounce (30g) of salt to your system as soon as possible, this will increase your hardness a little perhaps enough and reduce osmosis stress on your fish by reducing the effects of nitrites and producing more slime coat on the fish. Sea salt is fine even table salt will be ok however, there are ‘aquarium salts’ or conditioning salts designed for goldfish they will increase hardness to the desirable levels and add a blend of essential electrolytes to your system; but essentially it is very similar to common table salt.

If you can try feeding you fish some frozen blood worms or something similar this will help pick them up as well.

[Hamish]

I just had another thought - are you using tap water? Perhaps the chlorine or chloramine has damaged the fish?

[Jonathan Dyer]

Thats right Hamish but would'nt that go without saying. If that was the case then almost all of the fish would be dead by now, they would'nt survive to long in treated water, however, there are many products on the market to remove chlorine and the like; 'Prime' comes to mind here in Australia it is very good it also removes nitrogen from the water as well.

[rdiaz63]

Hi everyone,

Thank you very much for your support on this problem. According to the information provided by Nick, I guess my problem might be the PH. Here in Puerto Rico the temperature range between 84 and 98 degrees Fahrenheit on midday. So probably the ammonia concentration still causing my fish death.

I used tap water, but I treated with chlorine remover and conditioner before insert the fish. I also use liquid bacteria to boost the system.

What I'm going to do is trying to control the PH levels during this week and reports the progress to see what happens...

Thanks

Robert

[Hamish]

Thats right Hamish but would'nt that go without saying.

That depends on peoples level of fish keeping knowledge I guess.

If that was the case then almost all of the fish would be dead by now, they would'nt survive to long in treated water,

If the chlorine levels were low would it kill the fish right away? Or perhaps just weaken them so they die later?

there are many products on the market to remove chlorine and the like; 'Prime' comes to mind here in Australia it is very good it also removes nitrogen from the water as well.

How safe are these to use in food production? I am lucky in that my water is treated with chlorine (not chloramine) so I am able to bubble off the chlorine with an airstone in a couple of days. You cant do this with chlorimine. For smaller systems a bucket of water sitting in the sun always ready to use for system top ups would work as a dechlorinator and avoid use of chemicals.