Flourish Excel... Low O2? HELP!

[Andrewz00]

ok maybe i am just psyching myself out.... but ive decided since i do not have a CO2 system that i would start using Seachem Flourish Excel.... i followed the dosing instructions to the "T".... but now it looks like my fish are moving their mouthes a mile a min, what looks like gasping for air...

background... 90 gal tank... planted... (just added new plants)

4 octopus plants
4 crypt wendtii
2 micro swords
and there are 9 other plants that i cant remember the name of and i threw out the receipt.

Zero surface agitation... (was told you dont want or need surface agitation with a planted tank because it would bubble all the CO2 out of the water.. is that correct?)

so HELP!!! are they really struggling to breath? how can i test the CO2 and O2 levels??

 

[Crepe]

You can have surface movement with excel, it's actually a carbon containing compound that when absorbed by plants, is processed the same way as CO2. Your fish are probably suffocating from just low O2, not high CO2.

Edit: Found the compound; glutaraldehyde.

 

[Andrewz00]

ok so it is FALSE that you DO NOT want surface agitation in a planted tank? should i introduce a air stone? or just point the spray bar from the Eheim 2217 towards the surface?

 

[Crepe]

You don't want surface movement if you inject CO2 from a canister or DIY, in this instance you're dissolving gaseous CO2 in water. Surface agitation imparts kinetic energy to the CO2 molecules and H2O molecules, breaking the weak intermolecular forces between the CO2 and the H2O; the resultant movement causes the CO2 to rejoin the atmosphere. What other CO2 that is mixed into the water becomes CO3- and H+ ions, which is why injecting CO2 drops pH as pH measures the logarithmically scaled lack of H+ ions.

Chemistry aside, glutaraldehyde won't rejoin the atmosphere due to surface agitation.

 

[Andrewz00]

thanks for the chemistry lesson! LOL so long story short...

im pointing the return spray bar towards the surface!

 

[mfdrookie516]

Unless you are injecting CO2, surface agitation will only add CO2 to the tank, not subtract it.

Surface agitation tend to equilibrate the CO2 level with room air. If you are adding extra CO2, then sure, that would drop the CO2. But if you are not, then agitation is going to replenish the CO2 your plants used, and is actually a good thing.

Looks like Crepe has the chemical aspect... here it is in an easy way to understand

 

[mgamer20o0]

i believe excel can lead to low o2 levels but normally thats only at 3-4 times the normal amount.

you can prob get away with not even adding excel. doesnt seem like you have many plants at all. normally in a tank where you are injecting co2 gas the plants make plenty of o2. with zero surface agitation and only a few plants they cant keep up.