Low oxygen

[charter]

The last few days my fish in the morning are at the top gasping for air. The CO2 is around 6.5-6.6 and the drop checker is green. I cut back the CO2 and this did not change anything but the PH to 6.7 I changed the drop checker solution and re calibrated my PH monitor . Because of the drop checker reading a constant green. I have not tested the KH. I assume it is still at 5 degrees. Is there something I am missing?

 

[BHornsey]

Do you shut off CO2 at night? If not, get a solenoid and time it on an hour before the lights.

 

[Professor Myers]

What is the flow rate through the tank, and do you use a surface skimmer ? 1st. line of action is shutting down the Co2 at night. Second is to increase the circulation. Third is to start using a surface skimmer. In theory with surface skimming and 5X circulation your air/water interface is infinite. This is a fallacy of course, but it certainly doesn't hurt ! Over 10X circulation the scenario generally flips the other way. HTH. Prof M

FTR the Boast of trickle filters providing luxurious o2 levels is disproportionate. 5X to 10X circulation with a common canister filter will accomplish more in less time.

Even under hyperbaric circumstances the trickle filter can be out paced by simply increasing the flow rate. Been there ! Done that !!!

 

[charter]

I know some like to use a solenoid however I have been very successful letting the CO2 run 24 HRS. and using air pumps to out gas the CO2 at night. I am using two XP3's for the circulation. I don't have a skimmer. I have not changed my routine so I'm not sure why this has started. I will clean out a filter early to Increase the flow rate. Thanx.

 

[Professor Myers]

"I have been very successful letting the CO2 run 24 HRS".

I thought you said the fish appeared to be gasping in the morning ? I misunderstood... At first I thought you were concerned with their respiration. Just a few degrees temperature difference in warmer months could spell certain disaster once the o2 scale is tipped ! When is the best time to address that ?

In another of your tanks it would appear that the plants might be nutrient/Co2 defficient ? While the lighting may appear to be lame it is not neccessarily insufficient.

Plants respire Co2 at night, and utilize oxygen. The PM o2 cycle is every bit as important as the AM Co2 cycle. The o2 is not elective it is an actual requirement. The Fish seem to enjoy it immensely as well !

One of the perks of shutting down Co2 at night is that you can achieve higher oxygen at night, and this allows you to run more luxurious levels of Co2 in the daytime with less stress to the livestock. If you are gravely concerned with radical swings in PH through the cycles please bare in mind that a range of 10 degrees or more is not uncommon in nature at all. This usually occurs in the daytime during photosynthesis, but can be exploited in aquarium closed system enviornments at night to benefit both the plants and the livestock. You also save 1/3 to 1/2 of your Co2 in the process.

Sometimes less is more...you cannot fascilitate 1/2 of the process and expect successful results. You seem to have provided for water "quantity" over water quality at the expense of both the plants and fish.

When all else fails...Higher circulation can equal higher o2, and more "stable" Co2. Very Best of Luck, Prof M

 

[charter]

The Professor wrote "I thought you said the fish appeared to be gasping in the morning ? I misunderstood... "
You didn't miss anything, they do gasp for air due to low o2. I didn't know that warmer temps depleted o2 from the water.
When I first started using CO2 I was using test kits and a Milwaukee PH controller with a solenoid and a timer. My inexperience caused the fish to stay at the top trying to get air. I went for help at a different website and was told to use timed air pumps and leave the CO2 running 24/7, the air pumps would out the CO2 leaving plenty of o2 in through the night. This was working well for the longest time. It is obvious I still have a lot to learn and that is why I became a member here.
The PH changes I'm being told is the reason that the Rainbows are dying, so I was trying to stop the fluctuation.
I will put the CO2 on a timer set to run 1 HR before the lights come on and 1 HR before they go out , is this correct? I will monitor the CO2 using a drop checker. Should I leave the air pumps in or take them out?
I am after top Quality Professor that's why I'm asking these questions. I will say though I don't understand why for so long what I was doing worked then all of a sudden started failing.
This tank has two XP3's running at 350 GPH.

 

[Professor Myers]

Go back and re-read Tom's TBR on oxygen in the planted aquarium.

Temperature, Altitude, specific gravity, PH all effect o2 levels. Still other events like ammonia, nitrite, and PH effect your livestocks ability to utilize o2. You could have super saturated levels of o2, but if nitrite were to reach toxic levels the hemoglobin would become bound with nitrite, and the fish would still suffocate.

The cooler the water the higher the o2 level, & vice/versa. Plants almost always get enough o2 at night, but if the dissolved oxygen were on the fence, and the tank were well planted, the plants will always get their o2 even if it's at the fishes expense, and fish require much higher levels of o2. So the plants win by default !

Still the fish could survive for quite some time with substandard o2, but you'd eventually notice the stress (Gasping at the surface) up to that point they may very well cope with it but may have a higher occurance of disease, and an increasing mortality rate.

Any of this ringing any bells ???

Many pathogens are commonly present in our aquariums every single day. The breaking point only rears it's ugly head when the fish become stressed.

FTR. Aeration doesn't actually increase the o2 per se. It simply drives off and degasses the Co2. While I'm sure the air pumps are effective, I suspect not adding the Co2 to begin with might be more efficient ?

Better still, shut off the Co2 and run the pumps at night !

If you want to push the Co2 envelope fine ! Just do it in the day time while the plants are hard at work converting it to o2. Co2 rarely kills fish. It's the lack of o2 that trips the scale.

As I said earlier my tanks range from 7.4 to 6.4 ph daily, but my o2 levels are almost always at saturated levels day or night, and my Rainbows are frumping like Bunnies !

How do I do this ? Well ? I shut off the Co2 at night for one thing, but I often use flow rates of 10X to 15X in my systems and the lower flow rates actually have trickle filters with hyperbaric air. My biggest challenges are generally housing/selling all the Cherry Shrimp and Rainbow fry. Supplementing food for my algae eaters, and culling/selling 10 to 15 gals. of plants each week. It's gruelling, I tell ya ! Prof M

 

[Tom Barr]

I'd just raise the spray bars up some and get more O2 24/7 in there.
You'll lose some CO2, but that's easy enough to add more.

Plants/algae etc can be addressed easily, dead fish?
Really really hard to cure them and bring them back from the dead.

If you use 24/7 CO2, I do not suggest it, nor do most folks in the know and well experienced, you will need to compensate with more circulation and surface movement.

Not quite breaking the surface........

Regards,
Tom Barr

 

[charter]

I have set the CO2 on a timer. The CO2 will turn on at 8AM and run until 7 PM. The main lights are on from 9 AM until 8 PM. Is this correct ?


Tom, should I raise the spray bar as you suggested now that I am shutting the CO2 down at night?


Professor M. would you clarify your filter system please, I haven't heard of this setup before and would like to learn about it.

 

[Tom Barr]

I just leave the spray up all the time, not enough to break the surface and cause air bubbles, right below that though.

You'll lose some CO2, but.........you gain some much needed O2 and the build up of CO2 is not as unstable/dramatic, so it's more controllable.

So just add buit more CO2, and stick with that.
Also, adjust the lighting to 10 hours a day, you really do not need more than this, a lot of algae response well to longer day lengths(11-12 or more-this day length change signals seasonal changes).

I think you should see better plant growth as well as cleaner/cleaner tank, give things a few weeks then decide.

Adding more current and keeping things pruned well will provide a higher degree of stability.

If you have 2x as much plant growth between prunings, then you will have far less current and movement, thus less O2 exchange etc.

Regards,
Tom Barr

 

[Professor Myers]

I have set the CO2 on a timer. The CO2 will turn on at 8AM and run until 7 PM. The main lights are on from 9 AM until 8 PM. Is this correct ?


Tom, should I raise the spray bar as you suggested now that I am shutting the CO2 down at night?


Professor M. would you clarify your filter system please, I haven't heard of this setup before and would like to learn about it.

A Trickle Filter/ Wet Dry Filter is basically a combination of both an oxygen reactor & ammonia tower, though neither component is purely effective as it's bastardized for water treatment.

In planted aquariums with Co2 it's best to raise the water level in the overflow, and seal the trickle tower to avoid degassing Co2. Since my tower is actually sealed air tight I drilled two ports in it to accomadate Co2, and air injection. Once the Co2 cycles off for the night a HP air pump evacuates the Co2 and pressurizes the tower beyond ambient air pressure to fascilitate oxygen absorption. I had intended to switch to tanked o2, but I've never found it neccessary. Too much pressure will craze the acrylic filter, so there are check & relief valves to relieve the excess. Likewise too high a flow rate tends to boost the PH too quickly for the Co2 to recover in the AM cycle.

I don't actually expect anyone to go to this extreme, but it was a fairly inexpensive experiment that actually worked...WTH ?

Honestly you can achieve higher o2 levels with a properly configured canister filter and excessive flow rates in less time. It could be done with a trickle filter...but the size and cost becomes prohibitive, and it can be difficult to achieve high flow rates with gravity drains. Grtz, Prof M

 

[charter]

I have made all the suggested changes . Somthing is wrong.The Babytears .Glosso and Watersprite have thinned out rather than fill out. I increased the ferts to double the amount I was adding. I am not seeing much of a PH swing overnight. I am only seeing pearling in the last hour or two before the first set of lights go out . The pearling stops soon after while the second set is on for the final hour. Because the PH is not raising overnight I have not increased it . The fish have not showed any signs of stress so that is a good thing.