pH morning and evening

F

Faramir

The twit from over the pond.
Nov 20, 1998
738
0
0
Chesterfield UK
Using CO2 injection, what sort of differences might one expect between pH readings first thing in the morning and just before the lights go out?

I only get a difference of about .1 - 6.5 against 6.6 (KH 4).

Actually, I might have to turn the CO2 down a bit, looking at the table. And there's me worrying about getting enough CO2 to react with DIY...
 
6.6 to 6.7 is good.

A small flux in pH is good for the am vs the pm times.
That's what you want.
If something looks funny in your tank, always check the pH and see what the CO2 is first before checking any of the other nutrients. This is especially true of DIY CO2 users.

Regards,
Tom Barr
 
Ta. I will cut the CO2 a bit - i.e. reduce the volume of the mixture.
 
Faramir, that's ideal. Especially for DIY. Don't mess with it. I find that each bottle change brings a slight difference in pH, I guess due to slight variations in mixture and therefore slight changes in concentration. But I shoot for 6.5-6.6 swings every time. With those parameters your plants will start to show significant improvement over time.
Len
 
Last edited:
The fish are gasping a bit in the morning - especially the beckfordi pencils. Everything else is fine - ammonia, nitrite zero, good circulation from a Fluval 304, and the gasping stops once the lights have been on for a bit. I think I'll have to drop the CO2 very slightly.
 
Fish gasping is a sign of too little O2 -- not high CO2. When you have a combination of a high plant load, high fish load and low surface agitation, it's not uncommon for there to be insufficient O2 to last both the fish and the plants through the night to the next photoperiod. Don't mess with your CO2 level, if it's where you want it. Rather run an airstone(s) on a timer during the night. We had that problem when we had our discus -- now that we have a small fish load, testing shows the O2 is plentiful in the early a.m.

Jared
 
It's a bit contentious though, isn't it - there's some old discussion archived on the Krib. It seems that high CO2 levels can inhibit uptake of O2.

Having said that, I'm also planning to add another fluorescent tube; I think that light is now the limiting factor; this will improve O2 production during the day and with luck give a larger reserve to last the night.

I'll leave the CO2 alone for now.
 
No it's not contentious.

O2 and CO2 act _independantly_ of one another in a planted tank with CO2.

Fish gasp for O2, seldom will you see them gasp even at fairly high CO2 levels.

They will gasp if you don't have some current on the surface, just don't over do it. Add some slight current to the surface.

Good plant growth and mass will produce large amounts of O2 and there's never any issue unless there's lots of waste and fish.

Gasping stops since the plants start giving off O2. If you have some current so that the water column does not get depleted at night, you should be fine. Try it and see. Unless you have a lot of fish, you don't need an airstone at night or a power head etc.

Regards,
Tom Barr
 
There is surface movement - the filter output is about half an inch below the water surface and you can see a surface current.

Despite my CO2 I'm not seeing pearling. My light is a little low, so I'm going to increase that. I'm sure the issue is getting a higher rate of photosynthesis, and light seems to be the limiting factor - it's currently a smidgen under 2W/gal.
 
If there's some surface movement, and the fish load is not too much, the gasping may be a sign of excess CO2. Generally it is not but you had pretty high CO2 levels there. 50ppm or so. You don't need that much to have good pearling and plant production which would help the fish even if the CO2 was high.
Since the CO2 is in good shape now, take a look at the NO3 next and add extra K+(KNO3 would add both nicely). Traces after this and finally PO4.
GH should be over 3. Get these in decent shape and you'll have good plant growth.

You can use a nighttime airstone/powerhead etc since the fish lhealth is of prime importance for now but get things taken care of.

Regards,
Tom Barr
 
You must log in or register to reply here.
AquariaCentral.com
Top Bottom