# EI, Low CO2 at Lights On.......Problem?



## Herbie (Jan 28, 2005)

I have been doing EI for a couple of years. It pretty much works fine for me in my heavily planted 20 gallon/A&H 1x55 PC/pressurized CO2 setup. I say pretty much as I occasionally have a fairly minor hair algae problem (nothing too out of control like some tanks I see) and also seem to get some green spot and/or dusty looking stuff on the glass. I am close, but would like to fine tune things and make that intermittent hair algae problem a thing of the past.

I know that Tom says that algae problems are almost always CO2 problems and I tend to agree. When I did DIY CO2, I had really bad hair algae and other types as well. I also know that it is said that high trace levels do not cause algae, but through trial and error I have determined that dosing traces at 'full' EI levels does lead to green spot and the dusty looking algae on my glass. Increasing PO4 to 1.5ppm per dose does not eliminate this. The jury is out on the hair algae, but it seems that increased trace levels have little or no influence on this.

I believe Tom and EI proponents when they say that the traces do not cause algae, but wonder if a really rich mixture can exacerbate an existing problem; specifically my low CO2 at lights on. At lights on my CO2 is at 6ppm and at two hour intervals it goes to: 11ppm, 22ppm, 28pp, 28ppm and 35ppm at lights off. I am wondering if the fact that CO2 is less than optimal for a decent amount of my 10 hour light period could be my problem. This has probably been brought up before, but I have read a lot and can't remember seeing anything on it. Perhaps turning the CO2 on 3 hours or so before the lights would be a good idea? If you guys think this could be something worth investigating, I'll go buy a timer and see if it helps.

I guess we should eliminate my dosing as a problem&#8230;.P and NO3 are not a factor in my local water supply&#8230;levels are negligible.

*Sun*(Water Change Day), *Tue*, *Thu*:
KNO3- ¼ tsp
Fleet- .60ml (~1.04 ppm)
On Sun I also add ¼ tsp K2SO4 and .5ml CSM+B..even though I know it is not necessary.

*Mon, Wed, Fri*
3.5 ml CSB+B*

*The last couple of months I have reduced the trace amounts to about .75 ml per dose and this does seem to have helped a great deal with the green spot and 'dusty' stuff on the glass. Plants still appear to be doing fine. That is a lot less than the recommended amount though and that concerns me a bit. CSM+B is mixed at 2 tbs to 500ml water.

Tank has 8 neon tetras, 6 lemon tetras, 2 black neon tetras, 1 dwarf gourami, 3 ottos, and 1 flying fox and 2 red nosed shrimp&#8230;fairly high bioload, I think, but not out of control


----------



## jude_uc (Feb 7, 2006)

Do you run an airstone or something? How do you lose so much CO2 during the night?

-Adam


----------



## MatPat (Mar 22, 2004)

Before jumping to any conclusions about traces or macros, I would look into the CO2 issue you are having. It is quite easy to take a visibly algae free tank and get algae simply by running out of CO2. I've done it many times  

How are you getting the CO2 into the tank, reactor, diffusor, etc?

If you have Green Spot it is either low CO2, low PO4 or both. In the past I have turned my CO2 on as much as 2 hours before lights on to make sure I am at 30ppm or better when the light comes on! If the Green Spot still does not go away, up the PO4 to 2ppm or better while keeping the CO2 high. You can increase the Fleet to 1ml per dose once the CO2 issue is corrected.


----------



## Herbie (Jan 28, 2005)

jude_uc said:


> Do you run an airstone or something? How do you lose so much CO2 during the night?
> 
> -Adam


Nah, no airstone. I don't think this ph swing is unheard of.



MatPat said:


> How are you getting the CO2 into the tank, reactor, diffusor, etc?


I am using a diffusor, but am going to give the venturi reactor a try. I have the powerhead, so why not give it a whirl  I am a little concerned about noise when the bubbles are chopped up, but like little projects.

I really did suspect it was a CO2 at lights on problem. I bought another timer today and will report back in a few weeks.


----------



## Edward (May 25, 2004)

Hi
What is your KH and how much does it change between water changes?

Edward


----------



## Herbie (Jan 28, 2005)

Edward said:


> Hi
> What is your KH and how much does it change between water changes?
> 
> Edward


KH of 105 with no measurable swing between water changes. PH should be pretty stable, well at least poor buffering is not to blame!!??


----------



## jrIL (Apr 23, 2005)

something is making you tank out gas pretty fast. How about surface turbulance. Is there alot or just a little.


----------



## plantbrain (Jan 23, 2004)

You are not getting enough CO2 in there to start with, even if the measurements are not correct, they have a relative relationship.

Inside 1 hour the CO2 should be near the 20-30ppm mark. I get pearling inside 2 hours on every tank I use CO2 on.

Generally this is due to the lack of surface movement(cannot add a high rate with the lights on), a lack of flow, mixing etc, adding more flow or adding the limewood diffusers in front of the spray bars etc can help. 

Regards, 
Tom Barr


----------

