[Rimlak125]

Hey!
I am new to this forum, and just made the transition over to CO2 injection and have a few questions -

tank details: newly set up 45g bow front (my 30 gallon cracked 4 nights ago and I did an emergency tank purchase and change), fluval 306 canister filter, lots of lighting (cannot remember specs off the top of my head), I have a bunch of newer plants in my tank now that I have upgraded but I wouldn’t say it is heavily planted right now, caribsea eco-complete substrate, and a new CO2 system.
Livestock: 8 neon tetras, 2 snails (watching them like crazy due to unexpected tank change)

currently starting with 6 hour light/co2 cycles due to the tank having to cycle again, and will gradually get back to 12 hours.

Issues:

1. perimeters at the end of 6 hours of CO2: ph 6.4, KH 4. Parameters with CO2 off for 18 hours: ph 6.6 and KH 4.
I am not getting a significant change in the ph at all, wondering if lack of surface agitation is a cause? ... which leads me to problem 2.
2. A bio layer is developing on the surface of the water and won’t go away. There is water circulation below - but definitely not a lot of surface action.

question:

would increasing surface agitation correct these issues? And what would be the best option: bubbler, powerhead, spray bar?

 

[Asteroid]

Well you first need to figure out approx. how much co2 you have. Without surface agitation you can retain alot of co2 overnight, I know my tank does. Are you using a drop checker? Take some water out of the tank leave it out overnight and shake it up a few times. You could also check your tap water PH and use that as a base. Let the sit overnight as well.

If you don't know your looking for about a 1.0 drop in PH between degassed/gassed PH which usually brings you to around 30ppm of co2.

 

[Rimlak125]

hey! My ppm co2 during the day is sitting at 30 with co2 on (with lights on), but it creeps closer to 40 by the end of the light cycle (it’s at 1 drop/second).
18 hrs of co2 off, ppm is sitting around 15, but I’m noticing over the last few nights, the overall ppm is slowly creeping up overall, with minimal to no ph drop and only dropping co2 to 15ppm (at the absolute lowest.

With the i player on the surface and minimal surface agitation, I’m wondering if there isn’t enough gas exchange at the surface when the lights are out and the tank is slowly retaining co2.
This tank is a bit bigger then my last one, so I’m wondering it that and circulation is the issue.

 

[xrayguy]

I would run an airstone at night. It would create surface agitation, and push your pH up a bit in the process.

 

[Asteroid]

hey! My ppm co2 during the day is sitting at 30 with co2 on (with lights on), but it creeps closer to 40 by the end of the light cycle (it’s at 1 drop/second).
18 hrs of co2 off, ppm is sitting around 15, but I’m noticing over the last few nights, the overall ppm is slowly creeping up overall, with minimal to no ph drop and only dropping co2 to 15ppm (at the absolute lowest.

With the i player on the surface and minimal surface agitation, I’m wondering if there isn’t enough gas exchange at the surface when the lights are out and the tank is slowly retaining co2.
This tank is a bit bigger then my last one, so I’m wondering it that and circulation is the issue.

OK, but how are you calculating that your getting 30 ppm of co2? What is your degassed and gassed PH? One drop/second is almost nothing in a 45g.

 

[jellopuddinpop]

Surface agitation is crucial in a CO2 enriched tank. You need to get rid of that biofilm. My suggestion would be a dedicated surface skimmer like the Eheim Skim 350 or Aquatop SSK-65.

Amazon.com : EHEIM Skim 350 Aquarium Filter : Aquarium Treatments : Pet Supplies
Amazon.com : AquaTop SSK-65 Aquarium Surface Skimmer : Pet Supplies

Here's a really great article that explains gas exchange in a really easy to understand way. I would read this (twice!).

Surface agitation in CO2 injected planted tanks - The 2Hr Aquarist