Backyard Aquaponics
A place to discuss aquaponics

Hello,

The fish in my system are dying rapidly. When I test the water all the level appear to be normal, however there is a thick layer of black muck at the bottom of the tank. When the muck gets stirred up (when I add buckets of water to the tank) then test the pH, the levels become crazy high.

Has anyone else had this problem? I removed my fish and put them into a different tank, but they are still dying off just as quickly they are small Tilapia.

As to the issue of water I am filling up buckets each day and letting them sit to let the chlorine work its way out of the water then I add those buckets the next day. Is this a pointless idea? I feel as though it makes no difference and is a lot harder on me then just filling the tank with the hose, ideas are welcome!

This is my first post, so I will say this in advance. Thanks for all the help!

Welcome to the forum Urbanvision, sorry to hear about the fish.

Letting the water stand for 24 hours is always good but you can probably get away with adding 10 to 20% of the total system volume per day, possibly more (without treatment). If it has chloramine instead of chlorine then I'd be a bit cautious. You haven't mentioned the size of the tank. If it's an aquarium tank is the bottom covered with pebbles. Any filtration and aeration?

As far as the bottom muck is concerned, if this is a regular tank I'd consider putting together something to suction this off the bottom and to your compost or garden. You might also be able to use a pond pump that handles solids to circulate the water through a filter to remove it.

It sounds like the muck has gone anaerobic. Any idea where this muck came from? Uneaten food, leaves, rock dust - it sounds like organic matter to me.

Pictures might be helpful to get an idea of how bad the problem is. Sometimes things that sound bad might turn out to not be all that bad.

Hope this helps.

Well the bottom tanks are 10x3x3.

I tested the water today and the pH remains at 6.6 in the bottom and top tank. Im still guessing it is the muck that is killing them. Not sure where it came from there was algae in the tank that they eat. At first we did feed them with fish food for awhile and then we stopped because they were not eating. So it could be old food, but it is strange that this muck is not getting filtered through, we have a filter and we do not have aeration but we have waterfalls from returning water sources. We don't have any rocks down there.

On another note, now the fish in my other system are dying. The pH has been low for awhile, I want to add baking soda to help raise the pH. Is this safe to do? I have never done it. I don't know how much is safe to add or how to add it.

Two of the fish I pulled out today had a pink or red spot on its belly. I have never seen one with a discolored belly like this...I pulled out two like that today. I am wondering if they are suffocating or something?


Thanks for your speedy reply. I am new to all this so I can use all the help I can get!

We really need pics of you system/s to help.

+1

and when you say the pH is low, what's the reading? Personally I wouldn't use baking soda, I'd use muriatic acid (aka Hydrochloric acid) and I wouldn't add it directly to the water in the system. I'd adjust any top up water needed to about pH 6.5 and let sit for a couple hours, test the pH again, adjust if necessary and finally add this to the system. It won't take much acid to adjust the water. You want gradual change of no more than 0.4 pH points in your system.

Scotty, I think he said his pH is low and he is trying to raise it, not lower it . Adding shell grit in a stocking where your water dumps into the ST can help, but if that's not enough to keep pH up, then you can alternate between adding small amounts of builders lime and potassium hydroxide to bring the pH up. Depends on the volume of your system - Mix a couple of spoonfuls with some water in a bucket and only add small amounts then check pH after a couple of hours. Don't increase pH by more than 0.4 units a day.

The thick layer of black muck on the bottom sounds like it food and waste that has gone anaerobic, especially if the pH shoots up when it is disturbed. This will be producing ammonia and hydrogen sulfide and other nasties that will kill your fish when mixed through the water column. You need to get rid of it if you are going to be disturbing it by adding buckets of water. Can you move your fish to another tank while you clean it out?

As Scotty says, you need to post some photos of your system and describe how it is set up (volumes, flow rates & direction, solids removal, growbeds, biofiltration etc) so that folks can give you advice.

@urbanvision Hi and welcome.

+1 Charlie, scotty435 and joc , we really need more information to provide you with any advice. For example, what is the reading for ammonia/No2/No3 as well as temperature? You probably need to siphon away the sludge at the bottom of the tank as advised by scotty and joc.

If PH on its own you are probably fine if it is at 6.6 but if you couple it with temperature you might have an ammonia lvl that is toxic to your fishes. Take a look at the attached pic to get a better understanding.



Regards

Wow thanks for all the great info. Unfortunately all the fish on that side of my system died. I tried to upload pictures, but it kept saying my file size was too big and I was unsure how to fix that.

I now have no fish in that system. I did raise the pH in the other system I have with agricultural lime. A little bit of that went a long way. I did have one fish die today, I am hoping the other fish beat it up and that this isn't going to start a trend. I tested all the water levels today and everything is on point. The pH is a little higher than normal, at 7.0. But i figured it will come back down.

So thanks for the help! I have new issues to deal with now.

Sorry to hear about the fish.

Here's a tutorial on posting pics to the forum in case you keep having fish problems - http://www.backyardaquaponics.com/forum/viewtopic.php?f=4&t=21754