How I DECIMATED my aquaponics system and I have no idea why!

[Jeff]

I don't know if this is a cry for help, or just my last ditch effort to figure out what the hell is going on.

BACKGROUND: I've had my established backyard system going fine for TWO YEARS now. In those two years, I don't think I've ever lost a fish. So aquaponics isn't exactly new to me. My system consists of a 110 gallon tank and three 40-gallon grow beds filled with hydroton.

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All of the sudden, roughly two weeks ago, fish began to die. Since the last 14 days, I've gone from 29 fish to about 8! Yes, you read that correctly.

The way it started was that I found about 6 dead ornamental fish (on the smaller side) all dead in the corner of the tank. Some were partially eaten so they may have been there a few days. Since I had so many fish though and never an issue, I hadn't been checking the water as much as I should.

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So my first thought was, "Oh crap, was there some kind of ammonia/nitrite/nitrate spike? What could have killed them?" I checked all those levels with my test tube kit, and the only thing that appeared high was the ammonia (possibly 0.5ppm). Perhaps the ammonia was high because of the dead fish sitting in there, but more than likely, I think it began to slowly rise because all the fish were growing larger, and contributing more waste to the system. I think having 29 fish in a system with only 110-120 gallons of water is too much (but didn't seem like it when they were all babies).

But I digress.....

What could have killed them? I know.....perhaps it's because I had hadn't vacuumed out any fish sediment that may have been collecting around the pump inside the tank. You see, my pump cycles water from the tank to the grow beds, but inevitably, any solids that don't get sucked up sit around the sides and back of the pump. Well, there was a mountain of sediment in there.....so I used a wet-vac and sucked it up.

Thinking that would have some positive impact, I was surprised when more fish started dying.....this time, some healthy LARGE goldfish.

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So I immediately went to the pet store with a sample of water, and had them test it. They said it looked fine, but the nitrates looked high. (NOTE: My nitrate readings at home looked fine, but the pet store used those little 5-on-1 test strips which indicated a high nitrate level. Strange, I thought.....possibly an error? I always heard those strips weren't that accurate.) Either way, they recommended a water change.

Now here is where I made my first big mistake. I did an aggressive water change (over 60% of the tank). My tank is about 100 gallons, by the way.

Up until this point, I've always just topped off water when it evaporated....never did a water change. Topping off always consisted of putting my hose into the tank and filling it until it was full (estimated about 10-30 gallons at any one top-off). Never did I ever put in any Stress Coat formula or Salt.


So after this drastic water change, within a few hours, I saw more "healthy" fish die. I believe that happened from shock: too much water changing places, and possibly a temperature difference from the hose?

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A few days later, after it seemed under control, I started to see my Koi dying. All water tests appeared to be fine (pH, ammonia, nitrate, nitrite). The water temp was in the 70's or low 80's, and that's never been a problem. Always had good water flow and oxygen being returned from the siphons.

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So like an idiot who means well, I decided on ANOTHER WATER CHANGE. This time, I took a bunch of 1 gallon plastic water bottles, filled them with water, let them sit IN THE TANK to get the temp acclimated, and then poured them in. I also added the right amount of Stress Coat formula and 1 ppt of salt.

I even built a new 15 gallon radial flow filter, to help collect any extra sediment from the fish bed and serve better filtration.

Despite all this, my fish are still dying (at least once per day).

I checked my ammonia and it appears a little high (between 0.25 - 0.5). I haven't fed the fish for 2 days now, and I have no idea why it's high. The only thing I can think of is perhaps the water changes from last week affected the nitrification cycle? What do you think?

Either way, I am totally helpless right now and have no idea what to do to stop the fish from dying. Any ideas?

[Aloha Don]

My system is much newer than yours but I had the same thing happen...All of a sudden my fish started dying...Unfortunately, my issue WAS an ammonia spike that registered on my test kits. At least that is what I am assuming killed them.
I did a 50% water change and slowed the fish feeding (never stopped feeding) - monitored until it re-stabilized.
I dont use the stress coat. I was not sure it is good for plants. ???
I know this is NOT what is happening in your system but in case others have similar issues...this is what worked for me.

[Jeff]

Thanks for the post. I look forward to what others might say as well. I am concerned if the higher ammonia right now (AFTER water changes and mass fish die off) may be due to my tank needing to cycle again? I never got rid of ALL water.....but I did change out a good portion of it. The media beds which filter the water are still in place, and I'm sure there's still nitrificating bacteria in there......but perhaps other members can comment if doing a large water change (or adding salt) can contribute to an ammonia spike (due to bacteria being removed, or neutralized by the new tap water).

[JCO]

I've thought about it quite a bit while on the road and can't really come up with anything but I would lay off the water changes. Have you checked your grow bed to see if it is getting clogged. That could cause a problem in the fish tank.

[Jeff]

JCO - Well I haven't a fish death in a couple of days. I think the ammonia was a little high, but any number of things may have attributed to it:

- Lack of initial water change
- Overfeeding

I think my over aggressive water change also did more harm than good by disrupting the bacteria cycle, and also shocking some of the fish, resulting in more deaths.

In the past couple of days, I have simply ADDED treated water (no more than 10 gallons a day) until the ammonia appears to be diluted a bit. I am also applying Stress Coat to the newly added water (which helps get rid of chlorine, chloramines, etc), and I'm also putting in aquarium salt into my sump to help treat the system for any parasites.

My question for you is this: I have NEVER cleaned out any of my grow beds, so I am sure there may be sludge and god knows what else at the bottom of them. But how can you clean a grow bed which has established plants already in them?

For example: In one of my growbeds, I have Serrano pepper plants. They're pretty established (being two years old), and they are great producers during the season. I fear that if I try to pull them out in order to clean the grow bed, it will damage the roots and they will never recover.

So are there any tips on how to clean a grow bed which has established plants in them? Someone on another forum suggested that to clean a grow bed, you can FLOOD it, try to swirl all the media around, and then drain it a few times until the water being expelled looks clean.

My only concern with that is:

1. Will that damage any plants which are in there?
2. Will that kill off any bacteria in the system (thus disrupting the nitrification cycle), or will all the beneficial bacterial still remain in the Hydroton and pick up right where they left off?

[JCO]

Someone on another forum suggested that to clean a grow bed, you can FLOOD it, try to swirl all the media around, and then drain it a few times until the water being expelled looks clean.

Bad idea! Since you have established plants in the grow bed that are producing annually, you don't want to disturb them unless you want to loose them.

One thing that may help to some extent if you are able to do so, change the location/way the water goes into the grow bed giving it new avenues to travel, but I will tell you now as I have stated in previous posts about cleaning out a grow bed, sooner or later you will have to or you are actually not doing Aquaponics. Instead you are watering a Mud Grow Bed that sooner or later becomes a raised grow bed of media and dirt.

There is nothing you can put into the grow beds that will clean out what has gathered there. In other posts, some members swear by placing worms in there but I know from past experience (46+ years of it), it doesn't work.

The only way to prevent the sludge build up is placing a large, well constructed sump tank between the fish tank and the bio-filter, before the grow beds to catch the uneaten food, fish poo and particulates before they get there and even then the bed will have to be cleaned every two or three years.

I wish I had better news but that's the way of Aquaponic grow beds which use media.

[David - WI]

If I have this right... the percentage of "un-ionized" ammonia goes up with temperature and pH; and unionized ammonia is more toxic at higher pH.

So, water temperature & pH are where I would be looking. (At 82F and a pH of 7.8 or 75F and 8.0 pH... 0.5 ppm of ammonia would be toxic).

[Aloha Don]

JCO - wont scuds help clean out the GBs???

[JCO]

Scuds can help keep an AP system clean but they can't perform miracles. If the system is already over the hill, they could maybe help some but never enough by themselves to correct a problem.

[Jeff]

JCO - You mentioned changing the direction of the water. I think I have done that to some degree in the past. For example, instead of it just pouring straight into the grow bed, I attached a 90 degree elbow and extended the output to another area of the tank. If I ever want to change directions, I simply can twist this pipe 180 degrees, and wallah: it will now be on the opposite side of the tank.

Of course, like you mentioned, that doesn't really CLEAN anything, so eventually I will have to clean the grow beds.

But I guess back to my original question: Are there any recommendations on how you would clean out a grow bed that has established plants in there? I just struggle with how to do it and not completely destroy some of the plants. I guess it's going to be somewhat of a compromise: if you want to keep perennial plants, you have to be willing to sacrifice the ability to easily clean the grow bed. Correct?

Thanks for all the help. If I have time, I will post a youtube video just to show what my two year old system looks like.