co2 diffuser placement problem

[lossam8199]

hey guys I need some suggestion for the ideal placement of co2 diffuser in my planted tank.

this is what I have on my 46 gallon:
20oz pressurized co2
a glass diffuser
two fluval c4 HOB filter( little wet&dry system in there).
a 425 gph circulation pump.
a fluval co2 drop checker

from these equipment, what's best place I can place the diffuser?

I have heard people place the diffuser under the filter intake, but I think that wouldn't work for me, because the wet&dry will off gas many co2?

should I place the circulation pump right above the diffuser? I have tried that it blows bubble all over the tank, but I can't tell if it's really dissolved or not.

I have lots of agitation at the surface due to the HOB filters, what's the best way to minimize the off gas co2?

I'm really frustrated, because I didn't see much improvements on my plant growth, pls help.

one more question, where should I place my drop checker, will the tiny co2 bubble been blowed around trap under the drop checker, and influence the reading ?

 

[Brian_Nano12g]

A 46g is a pretty tall tank so you have a good amount of vertical room for CO2 to dissolve in the water column. I'd probably keep the diffuser as low to the substrate as possible, and near the circulation pump. Keep the drop checker on the opposite end, not too close to the diffuser. Also, keeping the water level high will help reduce surface agitation and off-gassing.

Changes made in our tanks don't usually get noticeable right away. It make take days to weeks to see if minor adjustments to light, CO2 injection, and ferts make any positive effect.

With that said, what are your lights, plant species, substrate, and fert regimen? How long have you had the CO2 up and running? Do you have the proper amount of CO2 injection to get your drop checker lime green (~30ppm)? Is CO2 constant or on a solenoid valve or pH controller?

 

[lossam8199]

A 46g is a pretty tall tank so you have a good amount of vertical room for CO2 to dissolve in the water column. I'd probably keep the diffuser as low to the substrate as possible, and near the circulation pump. Keep the drop checker on the opposite end, not too close to the diffuser. Also, keeping the water level high will help reduce surface agitation and off-gassing.

Changes made in our tanks don't usually get noticeable right away. It make take days to weeks to see if minor adjustments to light, CO2 injection, and ferts make any positive effect.

With that said, what are your lights, plant species, substrate, and fert regimen? How long have you had the CO2 up and running? Do you have the proper amount of CO2 injection to get your drop checker lime green (~30ppm)? Is CO2 constant or on a solenoid valve or pH controller?

my lights are two 36 inch finnex ray 2 led planted lights.

substrate is 40 lb of ecocomplete with few root tabs under S. Repen

plants are ludwigia narrow leaf, S.repen, pogostemon helferi, cyperus helferi, and crypt undulata.

my co2 is with a solenoid regulator, and on timer with the lights, 9 hours a day.

my ferts is dosing flourish once a week, flourish trace and iron twice a week.

my dropper checker seems like light blue, and I see few tiny co2 bubbles trapped under the gas pocket of the drop checker.
also my tank now is set at 86F to treat ick, does that affect the co2 content in water?

 

[Brian_Nano12g]

Well your light is certainly going to be pretty high... co2 duration sounds about right. You might have to cut back on the photoperiod until you dial in your co2 otherwise you'll most likely run into algae problems.

I think the main problem is your fertilizer regimen. You're missing the macros! Those are super important, NPK.

I would recommend switching over to dry ferts when you can. It's more comprehensive and a lot cheaper to use. I use PPS-Pro.
PPS-Pro | Aquarium Fertilizer | Green Leaf Aquariums

I actually ran 2x Finnex Ray 2 over a 26g Bow Front for a bit. To my understanding, our tanks are the same height and only differ in the length. So IME, I had a CRAZY amount of growth with CO2 and the Ray 2's. It was actually a little too much light because it grew plants and algae nuts!

I don't think temp has any affect on CO2. Good luck on your ick problem! I know how that is...

 

[Fresh2o]

Regarding surface agitation, Look at post #2:
Quieter filter http://www.aquariumadvice.com/forums/showthread.php?t=239271

 

[aqua_chem]

I don't know that there's a whole lot of value trying to figure out what the optimal placement of a diffuser is; rather, it comes down to good placement vs bad placement a lot of the time. Good placement for you would be anywhere the bubbles are swept throughout the tank. I had an atomizer that I had at mid-height in a 40 that was placed such that the water was actually moving down the side at that particular place and the flowing across the substrate, which worked pretty well. It might come down to experimentation with your drop checker to find a spot that works well for you.

I have lots of agitation at the surface due to the HOB filters, what's the best way to minimize the off gas co2?

The best answer here would probably be "don't use a HOB", but that's not always very practical. Probably the best way to minimize surface agitation would be to keep your tank topped off such that there's as little turbulence as possible in the outflow.

I'm really frustrated, because I didn't see much improvements on my plant growth, pls help.

What's your drop checker reading? It's already been touched on, but you may also be having a fertilizer issue without dosing dry ferts with that much light and co2, assuming the latter isn't a problem.

one more question, where should I place my drop checker, will the tiny co2 bubble been blowed around trap under the drop checker, and influence the reading ?

Unless you have your diffuser directly below it, I don't see it being an issue. It probably is overestimating to some extents, but not enough that you're going to be running into problems because of it, as drop checkers aren't really precise enough to tell the difference or account for it.