All times are UTC + 8 hours




Post new topic Reply to topic  [ 6 posts ] 
Author Message
PostPosted: Mar 31st, '17, 22:14 
Offline

Joined: Sep 21st, '16, 22:29
Posts: 6
Location: Kansas, USA
Gender: None specified
Are you human?: YES
Location: Kansas, USA
So this is our second time ordering tilapia fingerlings and...neither has worked out very well. We've had this batch since March 9th. They were doing quite well at first, and we went over a week with no mortalities. Our levels were all perfect when we first received them, and we monitored them very carefully. We started with 125 fish, and so far have lost about 46 of them. The concern is that the last time we got babies, we ordered closer to 500 and only 1 survived (he's still alive and kickin, though).

Our levels currently:

pH: 6.8 (a little lower than ideal, but we've been nervous to treat it in case it stresses them out)
Ammonia: <0.25ppm
Nitrite: 0ppm
Nitrate: 80ppm

The fish themselves appear healthy and are eating twice a day with much enthusiasm. We have okra growing over the tank that are also doing quite well. The fish have been growing and seem completely fine with no abnormal behaviors, right up until we find them dead.


Top
 Profile  
Reply with quote  
    Advertisement
 
PostPosted: Apr 1st, '17, 01:31 
Offline
Moderator
Moderator
User avatar

Joined: Aug 26th, '10, 07:17
Posts: 7563
Gender: Male
Are you human?: YES
Location: Oregon, USA
Water temp?

6.8 is fine for Tilapia. Do you have a UV sterilizer hooked into the system?

With apparently no signs of disease I would suspect either that they had a problem with some physical parameter - spike in ammonia or nitrites, problems with lack of oxygen, problems with drastic swings in pH, some toxin getting into the water, OR that they have some internal infection. A UV Filter hooked to the inflow into the tank might help with this last one and prevent other fish from being infected. It doesn't need to be permanent, you just need to get control of the situation. Based on your previous experience if it were me, I'd probably get the UV Filter.


Top
 Profile  
Reply with quote  
PostPosted: Apr 12th, '17, 19:46 
Offline

Joined: Apr 7th, '17, 06:47
Posts: 1
Gender: Male
Are you human?: yes
Location: CQ australia
what you basically need to do is find some way of buffering your water. We use mollusk shells (without the mollusks) in our biofilter. the nitrosomas and nitrobacter actually live on their shells and the shells are gradually dissolved into the water providing a carbonate buffer to neutralize your pH.
Stocking wise 60Kg/L/hr is an upper limit and 3% biomass/day as a feed guide.
Zero Nitrite is good and the nitrate levels will be absorbed by the shells.
The fish exhale ammonia and the bacteria convert it to nitrate. We use a tower type biofilter filled with layers of shell and a natural updraft of fresh air. It is essentially a biofilter that acts as a gas scrubber (NH3 scrubbed out from the top and O2 scrubbed in from the bottom).

best of luck


Top
 Profile  
Reply with quote  
PostPosted: Apr 21st, '17, 14:18 
Offline
Bordering on Legend
Bordering on Legend

Joined: May 31st, '15, 17:38
Posts: 317
Gender: Male
Are you human?: yes
Location: Natalia, Texas
jimko wrote:
what you basically need to do is find some way of buffering your water. We use mollusk shells (without the mollusks) in our biofilter. the nitrosomas and nitrobacter actually live on their shells and the shells are gradually dissolved into the water providing a carbonate buffer to neutralize your pH.
Stocking wise 60Kg/L/hr is an upper limit and 3% biomass/day as a feed guide.
Zero Nitrite is good and the nitrate levels will be absorbed by the shells.
The fish exhale ammonia and the bacteria convert it to nitrate. We use a tower type biofilter filled with layers of shell and a natural updraft of fresh air. It is essentially a biofilter that acts as a gas scrubber (NH3 scrubbed out from the top and O2 scrubbed in from the bottom).

best of luck


Sounds like you have something unique used as a bio-filter. I'm very much interested to see what you have and would like to see some diagrams.

My main interests are along the same lines, such as using a Mechanical filters to remove solids from the waste water.

MT, first done anerobic, second done aerobic before being used.


Top
 Profile  
Reply with quote  
PostPosted: Apr 22nd, '17, 03:40 
Offline

Joined: Apr 22nd, '17, 03:38
Posts: 8
Gender: Male
Are you human?: YES
Location: Europe, Scandinavia
On the subject of fixing ph, reducing acidity, why would adding magnesium or calcium to the water, or something alike, not work? Am I being stupid? I'm a newbie.


Top
 Profile  
Reply with quote  
PostPosted: Apr 22nd, '17, 17:41 
Offline
Moderator
Moderator
User avatar

Joined: Aug 26th, '10, 07:17
Posts: 7563
Gender: Male
Are you human?: YES
Location: Oregon, USA
There really isn't a pH problem here CP so there's no need to adjust the pH but FWIW the form that you add the Calcium or Magnesium has a lot to do with the effect it has on pH. Normally you'd add something like Calcium Hydroxide or Calcium Carbonate to buffer the pH up. Carbonates are part of a buffer system and hydroxide is a strong base so most of the change in pH comes from these. I usually don't think of Calcium or Magnesium being used to change the pH.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC + 8 hours


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

Powered by phpBB® Forum Software © phpBB Group
Portal by phpBB3 Portal © phpBB Türkiye
[ Time : 0.139s | 19 Queries | GZIP : Off ]