dammit thats a good reply
bouncing cycled filter media from filters still going strong to ones that have crashed is a very quick way to get it restarted.
And ya, coral, marble, limestone or shellgrit on the bottem of the tanks will keep pH in a healthy range.
"Christian Lawrence" <clawrence At rics.bwh.harvard.edu> wrote in message news:mailman.192.1161704917.23274.zbrafish At net.bio.net...
The fact that you have nitrates suggests to me that your biofilter is/was operating; a system that is not fully cycled will not typically show nitrates b/c of the dynamics that occur when fish are first added to the system; VERY generally: 1)ammonia spikes, 2) population of Nitrosomonas increases, 3) ammonia levels decrease, 4)nitrites spike, 5) Nitrobacter increases, 5) nitrites decrease, 6) nitrates are produced.
What it LOOKS like from what you describe is that you are not buffering the water. As Joe mentioned, the oxidization of ammonia and nitrite by your biofilter drives the pH of the systems down, and if you don't buffer the water, the pH will plummet to the levels you are seeing.
Here's the other big problem: microbes in your filter have a preferential range of pH in which to operate; below 5.0 their performance will be very limited if it doesn't crash (not sure where the cut-off is, but at 5 m guess is that you're flirting with it).
So you've got to get the pH back up between 7 and 8 and then keep it there.
Two ways to do it: Most AHAB multirack sysystems I know of are equipped with sodium bicarbonate dosers and YSI-type controllers. When the YSI pH probe reads below a certain set value, it triggers a dosing pump to add enough sodium bicarb to get the pH above the setpoint and the pH remains within desired range. If you have this system, you need to make sure it is working properly. AHAB will help you with that.
If you are not equipped with such an automatic system, you can add bicarb directly. This will get the pH back up quickly, but the rapid change can stress fish, and you will have to do it constantly.
An alternative way to do it is to run crushed coral/aragonite in your system. Coral will dissolve in water below a certain pH, so it essentially acts as a source of carbonate/bicarbonate. Very simply, you can fill several AHAB tanks with rinsed coral, put them on the system with the flow on. It is important to maintain good water contact with the coral. So an even better way to do this is to outfit one of the cartridge filters on the AHAB with a chemical type filter that you can fill up with coral (instead of carbon, for example). But the tanks will work in the shorter term.
Adding coral will maintain your pH above 7, although depending on the number of fish you have and how often you feed, you will have to play a little with flow rates and amount of coral to get it there (start slow), but after that it will be very stable. Coral also contributes hardness (mainly Ca2+) to the water, which is important for fish health and development. Zebrafish also like hard water above 100ppm CaCO3. Coral will help you get it there.
On last thing: you should be flushing the ammonia and nitrites out of your system with frequent water changes until things stabilize (you start seeing zeros for ammonia and nitrite).
I can't explain why you don't see the problem in stand alones; from the info you provide, you must be buffering those systems somehow, or doing lots of water changes (easier to do bigger percentage in stand alones, etc.).
Let me know if you have questions. I'm glad to follow up off-list.
Brigham and Women's Hospital
Karp Family Research Laboratories 06-004B
One Blackfan Circle
Boston, Massachusetts 02115
On 23 Oct 2006 11:32:32 -0700, cosgood At odu.edu <cosgood At odu.edu> wrote:
Hello! I know many labs using multi-tanks systems - we recently
purchased ours from Aquatic Ecosystems. Unfortunately, our problems
began almost as soon as we transfered our first, originally kept in
stand alone glass aquaria, into their new homes. What we see is loss of
embryo viability - the vast majority die within 12-24h after collection
from a separate breeding tank.We think the problem is with the
multi-tank unit - the water pH runs low (@5), we have have levels of
ammonia and nitrates - and we see none of this problem with our
individual tanks. So something to do with the multi tank unit, whether
it's the pump system, the plastic used in the tanks or the reservior,
no clue. Has anyone out there had similar problems? More importantly,
how did you resolve your water quality issues? We've not had much luck
in getting useful advice from Aquatic Ecosystems. I'm hoping the zfish
community will be able to suggest some approaches we could try out.
Resolving the pH problem is probably the simplest issue, but it is a
puzzle that we don't see the problem in stand alone tanks!
Thx for your time - Chris
Zbrafish mailing list
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Brigham and Women's Hospital
Karp Family Research Laboratories, 06-004B
One Blackfan Circle
Boston, MA 02115
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