Problem with bare bottom tanks...

[Bucky]

As I started an attempt on raising a third batch of danio fry...(I'm just
begining to get into spawning egg-layers) I came accross the same problem I
had the first two times...hopefully some of you can help me.

The spawning tank(s) I set up were as follows. Water from established 55
gallon CO2 injected community tank (Nitrate 20ppm, nitrite 0 ppm, hardness
300 ppm, Alkalinity 150 ppm, ph of 6.6-6.8) java moss, sponge filter from
well established Endler tank. Bare bottom.

A black net with decent sized holes went in next just under about 5 inches
of water. It allows the eggs to fall through, and keeps the danios out.

Conditioned female went in followed by a male, spawn at first light with a
couple hundred eggs or so lying on the bottom. Adults removed, net removed.
A few unfertilized eggs fungus...no biggie. Hatch within 4 days, free
swimming in another 2 days, immediately begin to feed with microworms.
Now, right about this time the PH takes an amazing swing that is off of my
chart. From what I can gather, it jumps up close to 8.4. Just a couple
days ago it was 6.8. All other reading are the same as before. With nothing
in the tank, why would the PH jump to such a high level?? Of course most
fry die leaving me to raise but 4 or 5. They seem to make it just fine
after I take them out and put them in a breeder net in the 55 gallon tank.
I dont want to try and raise 200 fry in a breeder net.

This has happened 3 times in a row and it's getting frustrating.

The only thing that comes to my mind is the amount of oxygen in the water
now, due to the sponge filter bubbling, makes the ph skyrocket like that.

Any advice????

[Mean_Chlorine]

Thusly "Bucky" > Spake Unto All:

>This has happened 3 times in a row and it's getting frustrating.

Well, the water _can't_ change pH spontaneously. It's something you've
added or which somehow gets into the tank - ie did you perhaps change
airstone? Could some detergent or similar have gotten into the tank?
Could condensed water be dripping from the canopy into the tank?

There is another alternative, although it's a long shot, and that is
if the water in your main tank really has pH 8.3, and you've lowered
it solely using CO2. When that water is transferred to the breeding
tank, the CO2 will be removed by the aeration, and pH will bounce back
to 8.3. I doubt that's what's happening, though I guess it's possible.
You can test this by taking a sample of your water, aerating it
heavily for a few hours, and then measuring pH.

However, it wasn't the high pH in itself which killed the larvae, 8.5
is well within the limits for zebra danios. There was some sort of
toxin in there as well. Ammonia perhaps.

[Bucky]

"Mean_Chlorine" > wrote in message
...
> Thusly "Bucky" > Spake Unto All:
>
>>This has happened 3 times in a row and it's getting frustrating.
>
> Well, the water _can't_ change pH spontaneously. It's something you've
> added or which somehow gets into the tank - ie did you perhaps change
> airstone? Could some detergent or similar have gotten into the tank?
> Could condensed water be dripping from the canopy into the tank?

The tank is in a back bedroom that we rarely go into. Not close to any
bathroom, washroom...etc. No detergent could have gotten into the tank.
There is no canopy on the tank either. Just a very dim floro tube lying
crossways over the tank. No airstone...end of hose plugs directly into top
of sponge filter.

>
> There is another alternative, although it's a long shot, and that is
> if the water in your main tank really has pH 8.3, and you've lowered
> it solely using CO2. When that water is transferred to the breeding
> tank, the CO2 will be removed by the aeration, and pH will bounce back
> to 8.3. I doubt that's what's happening, though I guess it's possible.
> You can test this by taking a sample of your water, aerating it
> heavily for a few hours, and then measuring pH.

My water right out of the tap is 7.0. I have measured it numerous times.
Could aeration on the tap water cause the ph to rise, or when it comes out
of the tap is that it's "real" PH??

>
> However, it wasn't the high pH in itself which killed the larvae, 8.5
> is well within the limits for zebra danios. There was some sort of
> toxin in there as well. Ammonia perhaps.


I have thought about ammonia poisoning also. My ammonia test kit is due to
be dilivered on Wed. or Thursday. There are approx. 100 eggs lying on the
bottom of the tank now...I can see the larvae turning inside them.
Hopefully I can get at least 50% survival this time.

One more question...when should I start doing water changes on the
fry/larvae? I have read that I shouldn't change the water before they are
at least 2 weeks old (so I haven't)....but maybe that is the problem?

[Dan White]

"Bucky" > wrote in message
...
>
> "Mean_Chlorine" > wrote in message
> ...
> > Thusly "Bucky" > Spake Unto All:
> >
> >>This has happened 3 times in a row and it's getting frustrating.
> >
> > Well, the water _can't_ change pH spontaneously. It's something you've
> > added or which somehow gets into the tank - ie did you perhaps change
> > airstone? Could some detergent or similar have gotten into the tank?
> > Could condensed water be dripping from the canopy into the tank?
>

I don't know much about fish, but if fish excrete ammonia, ammonia will
raise the pH of the water when it forms ammonium hydroxide, particularly if
there isn't much in the water to buffer the pH. Your test kit would have to
show a level of ammonia and/or ammonium ion for this to be the cause.

http://scifun.chem.wisc.edu/chemweek/Ammonia/AMMONIA.html

dwhite

[Mean_Chlorine]

Thusly "Bucky" > Spake Unto All:

>My water right out of the tap is 7.0. I have measured it numerous times.
>Could aeration on the tap water cause the ph to rise, or when it comes out
>of the tap is that it's "real" PH??

Yes, it does happen, especially if it's well water, as that is often
supersaturated with CO2 (and almost oxygen free) when it comes up from
the ground. As I said, I think it's a long shot, but it's easy enough
to test, if only to eliminate the possibility.

>One more question...when should I start doing water changes on the
>fry/larvae? I have read that I shouldn't change the water before they are
>at least 2 weeks old (so I haven't)....but maybe that is the problem?

You'd be changing with matured tank water, the same water you used to
hatch them in? If so, that's the exact same water they're already in,
ie zero chance of water parameter shock, so I say change often and
start early.

Regarding ammonia... This may sound crazy, but sniff the water. If it
just smells organic, like decomposing leaves, then it's OK, but if it
smells nasty, has a clear, sharp, evil, tinge to it, then you likely
have dangerous levels of ammonia in the tank and you need to do large
water changes ASAP.
As I said, it may sound crazy, and it isn't foolproof, but our noses
are very sensitive to ammonia and can detect it in the low ppm range.

[Mean_Chlorine]

Thusly "Dan White" > Spake Unto All:

>I don't know much about fish, but if fish excrete ammonia

Whether the nitrogen waste is present as highly toxic ammonia or
slightly toxic ammonium is dependent on pH. Normally ammonia isn't a
concern in aquaria with pH below, oh, say, 7.5, because approximately
all the nitrogenous waste will be in the form of ammonium, but a
rapidly rising pH will convert all that ammonium into ammonia, and...
game over.

[RedForeman ©®]

|| The spawning tank(s) I set up were as follows. Water from
|| established 55 gallon CO2 injected community tank (Nitrate 20ppm,
|| nitrite 0 ppm, hardness 300 ppm, Alkalinity 150 ppm, ph of 6.6-6.8)
|| java moss, sponge filter from well established Endler tank. Bare
|| bottom.

Yes... if you're taking the water from a CO2 injected tank, lets say pH of
6.8, and putting it in a non injected tank, it will dissipate the CO2 and
the pH will rise to nearly 7.4... start using water that isn't CO2 injected
and your pH will stabilize...

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[Bucky]

"Mean_Chlorine" > wrote in message
...
> Thusly "Bucky" > Spake Unto All:
>
>>My water right out of the tap is 7.0. I have measured it numerous times.
>>Could aeration on the tap water cause the ph to rise, or when it comes
>>out
>>of the tap is that it's "real" PH??
>
> Yes, it does happen, especially if it's well water, as that is often
> supersaturated with CO2 (and almost oxygen free) when it comes up from
> the ground. As I said, I think it's a long shot, but it's easy enough
> to test, if only to eliminate the possibility.

It is actually "city" water with chlorine/chloramine and all that nice stuff
in there.....

>
>>One more question...when should I start doing water changes on the
>>fry/larvae? I have read that I shouldn't change the water before they are
>>at least 2 weeks old (so I haven't)....but maybe that is the problem?
>
> You'd be changing with matured tank water, the same water you used to
> hatch them in? If so, that's the exact same water they're already in,
> ie zero chance of water parameter shock, so I say change often and
> start early.
>
> Regarding ammonia... This may sound crazy, but sniff the water. If it
> just smells organic, like decomposing leaves, then it's OK, but if it
> smells nasty, has a clear, sharp, evil, tinge to it, then you likely
> have dangerous levels of ammonia in the tank and you need to do large
> water changes ASAP.
> As I said, it may sound crazy, and it isn't foolproof, but our noses
> are very sensitive to ammonia and can detect it in the low ppm range.

Hehe...sniffing water. Hope I dont get my nose to close, I may
drown!!...lol. Seriously though, I will smell my water. I have never
heard of that but sounds like a plan.