• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

My pH profile

Sacha

Member
Joined
3 Jan 2014
Messages
992
Location
London
I have just completed a pH profile for today.

qowv.jpg


Time is along the x- axis, pH is along the y- axis.

12:30 = Co2 ON

14:00 = Lights ON

21:00 = Co2 OFF

22:30 = Lights OFF


KH is approximately 2.7

According to a few charts, I am achieving approximately 30 PPM Co2 concentration around 19:00.

Does this profile look ok, and is there anything I can do to improve my Co2/ lights schedule?

Is the Co2 coming on early enough? At lights on (14:00), pH was 6.7. This equates to a Co2 concentration of approximately 16-17 PPM. Is that acceptable, or should it ideally be higher?

I appreciate any input.
 

Attachments

  • qowv.jpg
    qowv.jpg
    18.3 KB · Views: 100
Hi,

You should have a full unit drop by the time your lights come on, this is the most critical time to have the highest concentration of co2 in your tank when lights come one.

Another thing also to consider is the following, how many lights do you have on this tank if say you are using 4 x 54w t5 then let 2 x 54w go on at 14h00 and then the other 2 x 54w at 15h00

Reason for this is the plants needs to kind of warm up to starting working properly with the co2 to start using the food it makes.

The point I am trying to make is you need to try and have your co2 at 30ppm when the lights go on.

So your problem is probably that you dont have sufficient flow and distribution in your tank, this can cause the co2 not to distribute enough into your tank.

What method of co2 diffusion are you using this can also be one of your problems.

Please give us some more info regarding this.
 
Sacha, the deepest part of the valley in your graph should be at the time when lights are switched on... And I guess the pH drop could be improved as your KH is not really high. I recently did some pH readings to adjust the co2 flow in my tank with a kH that probably is around 10-12 and I finally managed to have a drop of 0,7-1... But this was done improving the flow (setting up a spraybar), reducing the amount of filtering media in the canister, increasing the bubble rate and changing to an atomizer system. Each change was a little improvement in my readings.
Another important thing to achieve is a stable pH once you have reached this deepest part on your graph, you want the high CO2 levels in your tank during the light hours and at least until some hours before lights are switched off.

I agree with Hannes that another way would be to switch on the lights little by little, so the CO2 demand is not so high at lights on and your plants will not suffer in case you do not achieve the optimum levels.

Not an expert, but I had to do most of this things in the last weeks :)
 
Is the Co2 coming on early enough? At lights on (14:00), pH was 6.7. This equates to a Co2 concentration of approximately 16-17 PPM.
This doesn't equate to anything. As discussed previously, you cannot use the table to determine absolute values of CO2. You need to forget about calculating CO2 and instead concentrate on looking at how the pH changes.

You need an injection rate increase because with that KH the pH should really fall rapidly. If the fish are suffering when you increase the injection rate then this tells you that your flow and distribution are suspect.

Cheers,
 
Thanks for all the replies.

Clive, I am reluctant to increase my bubble rate, because the drop checker is nearly yellow by the evening.

My flow and distribution are pretty good I think. I have a spray bar and an internal powerhead. The tank is 125 litres, and I have a 1000 lph internal, and a 1400 lph external. I recently switched from an in- line atomizer to an in- tank diffuser, because I don't like the micro bubbles that I get with the atomizer. So far I appear to be actually getting better distribution with the in- tank diffuser.
 
OK, well what do the plants look like? What do the fish look like? Is the DC filled with 4dKH water? What was the pH profile with the atomizer in comparison?

There are a hundred possibilities. CO2 is an art form. It is not just a button press. You have to be home to monitor the tank during an injection rate increase. You may have more headroom than you think, or you may need to play with the distribution via placement of the pump outlets.

Cheers,
 
The fish are fine..

The plants only start pearling in the evening, maybe 6-7 pm.

Yes 4dKH in the drop checker.

I never did a profile with the atomizer so I can't compare.

Lighting is 2x 28w T5
 
Hi,

You should have a full unit drop by the time your lights come on.


I keep seeing this advice on this forum. To me it seems very odd.

A full unit drop in a tank of KH 2 equates to a minor increase in Co2.

A full unit drop in a tank of KH 12 equates to a much larger increase in Co2.

How can this advice possibly be correct, when every tank has a different buffering capacity? A "full unit drop" will equate to a different Co2 increase in every tank...
 
The rest of the advice goes like this:
"If you have a low KH then you need a much larger drop by lights on"
"If yuo have very high KH then you may not need a 1 unit drop. A 0.5 unit (or so) drop may suffice"

Few people in UK have low KH, so generally a 1 unit drop is the target.

If your fish are fine then you can improve the injection rate, but be there to monitor.

Cheers,

The plants only start pearling in the evening, maybe 6-7 pm.
Ideally, plants should be pearling by about 1 hour after lights on.
HOWEVER......if you are not having any CO2 related algae then the advice is to leave things be.

This MAY become a problem as the plant mass increases, but right now, if the plants are fine and if the fish is fine then ignore all the advice. If you have a problem then pay attention to the advice.

Cheers,
 
Thanks for all the advice.

I think today I will set the co2 to come on/ go off 2 hours before the lights as opposed to 90 minutes. I will also slightly increase the bubble rate.

If the drop checker goes yellow, I'll turn it back down?
 
Clive, I don't have a *problem*. I just want to completely optimize the Co2 injection
 
I have learned from our expert Clive:) that a Drop checker is only a rough guide, and that your fish will tell you at the end of the day if your co2 is to high then just turn it down a bit until they are fine.
 
By the time the fish tell you, they are already suffering. Ideally I Don't want to get to that point
 
It looks as if your PH max to min drop happens over 5 or 6 hours? That's a problem i'd say?

My gas comes on at 1.15pm ph7.4 and by 3pm (lights start ramp up) it's ph6.3. There it stays until well into light ramp down at 9.30pm (gas off 8.20pm).
 
Well today I have set the Co2 to come on/ go off 30 minutes earlier, and I have slightly increased the bubble rate. I have started a pH profile but I was only able to take the first reading at 12.15 (Co2 comes on at 12), so I don't know what the pH was at 11 am.
 
But it looks to be more an issue of how long your PH drops over as opposed to on/off timings. So if it comes on 30 minutes earlier but if it still takes 5 or 6 hours to drop this isn't much good.

A lengthy drop suggests to me (IME) poor dissolution method coupled with poor flow/distribution. For me putting a long spray bar on the rear and inline atty made all the difference...
 
I will switch back to my atomizer then. Although I really don't like the micro bubbles that it chucks out. I don't think my flow can possibly be poor. I have (rated) 2400 lph on a 125 litre tank.
 
Yeah it really is.

Just out of interest, what angle is your spray bar pointed at?
 
Back
Top