Hyposalinty, what went wrong?

[jcw]

I would have to agree if for nothing else than you never got that far into hypo.

The CO2 from the fish themselves could have led to your low pH problems. Rather than the RODI water.

There was a very interesting article regarding oxygenation in home aquaria. And what they found was that certain tanks becames VERY depleted of oxygen at night. To the point where in a healthy appearing tank, the fish were swimming up to the powerheads at night to maintain oxygenation. The found that powerheads basically moved oxygenated water to unoxygenated places. You need a protein skimmer to adequately oxygenate some tanks. Sounds crazy considering so many tanks run without a protein skimmer, but they did the experiments and had data.

 

[jcw]

Here's that article...

http://www.reefkeeping.com/issues/2005-07/eb/index.php

Very interesting read. (for me at least)

 

[sandwi54]

The CO2 from the fish themselves could have led to your low pH problems. Rather than the RODI water.

I agree with you on this. The build up of CO2 in the non-oxygenated water drove down the pH. Now that I know that the QT was not well aerated, I stand corrected that pH shock from RODI water is not the only cause for the fishes' deaths. Though, it is always a good practice to match pH when doing water changes nevertheless.

 

[125mph]

You need to break the waters surface with a powerhead to exchange carbon dioxide and oxygen,with a qt tank that small a air stone would work.

I see. So a powerhead running and moving the water but not breaking the water surface would not aerate it. That was a big mistake on my part. I had a small pump but I was concerned about the aeration so I used a bigger pump thinking that would do the trick.

I assume in a small tank, a hob filter like a fluval where the water rolls back into the tank creates the aeration you're talking about?

 

[sandwi54]

I see. So a powerhead running and moving the water but not breaking the water surface would not aerate it. That was a big mistake on my part. I had a small pump but I was concerned about the aeration so I used a bigger pump thinking that would do the trick.

I assume in a small tank, a hob filter like a fluval where the water rolls back into the tank creates the aeration you're talking about?

To create enough oxygen, the HOB filter needs to be pretty large to be able to disturb the water surface enough. I have a big aquaclear 110 (500GPH) on my 30g QT and I still use an airstone to be safe. You didn't mention what types of fish you had. Tangs, being active open swimmers, require more oxygen than other types of fish. They are typically the first ones to suffer in non-aerated water.

Next time if you have a chance, go to a LFS right when they get fish in and acclimating. A lot of times you'd see tangs laying on their side gasping, while other fish seem to be doing ok.

 

[125mph]

To create enough oxygen, the HOB filter needs to be pretty large to be able to disturb the water surface enough. I have a big aquaclear 110 (500GPH) on my 30g QT and I still use an airstone to be safe. You didn't mention what types of fish you had. Tangs, being active open swimmers, require more oxygen than other types of fish. They are typically the first ones to suffer in non-aerated water.

Next time if you have a chance, go to a LFS right when they get fish in and acclimating. A lot of times you'd see tangs laying on their side gasping, while other fish seem to be doing ok.

So in the DT, the overflow and skimmer creates most of the aeration? For my new QT setup, I have a fluval c3 150GPH and a Hydor Korilla Nano 211 GPH. The fluval is splashes some water on the surface but Hydor does not. Maybe I should get a skimmer too to bring in air. I don't realy like the humming sound of air pumps.

 

[MrTuskfish]

You should be able to aim the hydor so it hits the surface a bit. I think airstones do more to help air exchange by just disturbing the surface than by introducing bubbles. You really don't need (or want) "splashing:" or bubbles to help air exchange; just some constant turbulence of the surface. PHs can usually take care of this, if aimed properly. If your water surface is rippled (for lack of a better word), rather than flat...you should be fine.

 

[sandwi54]

So in the DT, the overflow and skimmer creates most of the aeration? For my new QT setup, I have a fluval c3 150GPH and a Hydor Korilla Nano 211 GPH. The fluval is splashes some water on the surface but Hydor does not. Maybe I should get a skimmer too to bring in air. I don't realy like the humming sound of air pumps.

You are right. The overflow and skimmer create most, if not all, of the aeration, unless there are powerheads near the water surface blasting to create waves.

You don't need a skimmer for the QT as it's an overkill. All you need to do is place the koralia higher and point it towards the surface to break the water surface. Rembmer, oxygen is not brought into the water unless the water surface is agitated. Your fluval is probably not strong enough to create enough oxygen for a large number of fish, as 150GPH is quite gentle.

As you are already aware, keeping the tank water well aerated also prevents CO2 build up, which leads to pH drop.