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pH profile during start-up

pepedopolous

Member
Joined
22 May 2011
Messages
678
Location
Prague, Czech Republic
Hi there,

I'd just like some advice on my CO2 injection.

I set up a 40cm cube aquarium 6 days ago and I'm doing 50% water changes every morning at about 9:00.

CO2 = 9:00 - 20:00 (I guess I could finish earlier???)
Light = 12:00 - 17:00

I'm not sure if I'm injecting enough CO2 because I'm using Amazonia which is said to reduce pH to about pH6. However, adding tap water increases the pH.

pH of water straight out of the tap = 7.37

Aquarium water pH at 9:00, before water change = 5.68

After water change = 6.17

pH at 17:00 = 5.40

I have a drop checker which is always lime green or yellow later in the day. It's difficult to make judgements based on the plant health because unfortunately, many of them were in poor health (melting) when I received them. I would say they are hanging on although the crypts are melting of course, even though they were in perfect health!

Thanks,

P
 
Hi there :)

hard to say without knowing your KH. But I think you should have bigger drop of PH definetly.

Few points:
yes you can switch off your CO2 one hour before lights go off.
It's hard as you mixing two water, however I think your water is not so hard as main.
Is the PH stable or it is dropping every hour few 0.1
Basically you should build enough CO2 over the two hours before lights goes on and then keep it stable over the full light period with minimum change.
How much is that hard to say without KH but I say you need more.

Vazz
 
Hi all,
With the usual disclaimer that I am not now, nor have I ever been, or are ever likely to be a CO2 user, but
I have a drop checker which is always lime green or yellow later in the day
You can ignore the pH drop, the drop checker has 4dKH "water" in it, and when it is yellow you definitely have enough/too much CO2.
CO2 = 9:00 - 20:00 (I guess I could finish earlier???)
Light = 12:00 - 17:00
You need to have the CO2 go off with/before the lights do, once the lights are off the extra CO2 is of no use to your plants, and could kill your livestock.

cheers Darrel
 
Hi all,
With the usual disclaimer that I am not now, nor have I ever been, or are ever likely to be a CO2 user, but You can ignore the pH drop, the drop checker has 4dKH "water" in it, and when it is yellow you definitely have enough/too much CO2. You need to have the CO2 go off with/before the lights do, once the lights are off the extra CO2 is of no use to your plants, and could kill your livestock.

cheers Darrel
Thanks for the reply, I don't have any livestock.
 
As Darrel said you do not need to have CO2 on out of light period. No matter if you have life stock or not you basically wasting your CO2 as plants without light have no benefit from it.
Thanks, I think I'll stop it before the lights go off then.

My reason for the extra time was to keep the level up so that even though much is lost overnight, it would be quicker to get to the correct level once the CO2 comes on again.

However, I think this is a moot point as I can't do a real profile until I can go a few days without a water change.

P
 
You changing your water parameters with the waterchange anyway so there no point to keep it up.
Also you have the two hours before lights go on to bring the CO2 on good level.
As you said I will be not worried too much before you stop to do so much waterchange.
Also is much easier for you to just up the CO2 if you find out that you do not have enough as you do not have to be worried about fish :)
 
I'm not sure if I'm injecting enough CO2 because I'm using Amazonia which is said to reduce pH to about pH6. However, adding tap water increases the pH.
This can be ignored.

I set up a 40cm cube aquarium 6 days ago and I'm doing 50% water changes every morning at about 9:00.
Stop doing daily water changes if you want to investigate your injection technique. First of all it's over the top and unnecessary, and, secondly it will disrupt your pH measurements, which is what you need to do in order to answer your question.

CO2 = 9:00 - 20:00 (I guess I could finish earlier???)
Yes, as mentioned you are wasting gas, will endanger your fish when you do get fish, so you need to at least simulate the technique and timing so that you have a better clue how the tank responds when you will have fish. If you want to add more CO2 then do so in the beginning prior to lights on and use the injection rate before and during the photoperiod to modulate the gas.
If your photoperiod is 1200 to 1700 then your baseline gas timing should be something like 1000 to 1600. Then take pH measurements at 30 minute intervals from 1000 to 1700. Make adjustments from there based on your KH. If the KH is less than 6 then you should get a 1-2 pH unit drop, if KH is 7 to about 11 then look for a 1 unit drop. These are just rough numbers to start with.


although the crypts are melting of course,
Why is this considered an "of course"? Crypts melting = poor CO2. So you have a lot of work to do. Forget about daily water change and get on with it man. Save your plants from extinction!

Cheers,
 
Thanks for your reply Ceg.

I thought that daily water changes are necessary when starting a planted aquarium. I've no intention of getting any fish until I nail the CO2, however long that takes.

I know you said in other threads that plants can get used to high levels of CO2, adapting to become less adept at capturing it. Bearing in mind that I really just want to grow the plants well, I'm not fussed about wasting CO2. If I inject CO2 24/7 and have a yellow drop checker 24/7, is it possible that I wont have enough CO2 for the plants? PAR is 30-40 and I also have floating plants (Azolla).

About the crypts- I may have damaged some of the stems when some uprooted and I replanted them in a hurry ;-/

Thanks again,

P
 
Pepe,
Daily water changes are not necessary. Of course they never hurt, and the idea of frequent water changes at tank startup is all about keeping the tank free of organic waste that becomes excessive after the plants are flooded. It also gives them a gulp of air while they are trying to play scuba diver. However, a 2X-3x per week for the first month or two works fine and is less stressful, especially for those who have large tanks.

More importantly, from your perspective is that you have to get the CO2 right. The reason you want really high CO2 after flooding the tank is that typically, the plants are grown emmersed and so their structure is adapted to be in air. Terrestrial leaves are not very good when flooded. They are normally tough and leathery and they are designed to resist water - NOT to soak it up. That's why the plants transition to submersed water absorbing tissues and why the emmersed form of a plant looks so much different .

So, in order to get even a nominal amount of CO2 through a leaf that is not well adapted to being flooded, we normally need much more CO2 injection than we will as the leaves transition. That's why there is so much die off when folks flood their tank. Even the people who prepare the tank via DSM are surprised by the amount of die off, when really it should be no surprise. Raising the injection rate to manic levels will help prevent the plant from disintegrating.

As the plants transition and get healthier you can then dial back the injection rate to sane levels.

I don't think 24/7 injection is as important as getting very high levels at lights on. Bubble counters are not even relevant at this time. If you use a torrid injection rate 24/7 all that means is that you'll run out sooner - and that is a hassle. It doesn't really gain you anything. Use the timer with a full open throttle needle valve and take the measurement so that you get to understand the scheme and the behavior of the gas. That's a much more valuable exercise than 24/7 injection.

Cheers,
 
New day, no water change. I've propped my pH meter on the spraybar and left it switched on.

I tested the KH using a JBL test kit (titration). According to that the KH is 2.

CO2 on 8:30, lights on at 11:00

Time ----- pH
08:30 --- 5.80 CO2 ON
09:00 --- 5.50
09:30 --- 5.17
10:00 --- 5.10
10:30 --- 5.07
11:00 --- 5.04
11:30 --- 5.04 (increased BPS)
12:00 --- 5.04 (increased BPS again!) Lights ON
12:30 --- 5.04
13:00 --- 5.02
13:30 --- 5.00

So I've increased the CO2 several times now, the BPS has never been low enough to count. Somehow, despite the low KH, I can't get the pH to drop 1 point in over 4 hours! The drop checker is strong yellow.

A picture to show the sorry state of affairs and flow distribution. Tank is 60l, filter is JBL 700 lph.
14988678875_c55c432514_c.jpg
 
I think that with such a low pH you never get one whole point down. Water acidification using CO2 has its limits. I guess you are not allowed to get under pH 5 (or so). Your pH is extremely low to start with! If you use hard water for couple of weeks, your substrate will saturate much earlier, and your pH drops won't be so dramatic.
 
Not to hijack but what is advised to use for the PH test. I thought test kits were the devil incarnate!
Although obviously it is key to know what the PH is. I have just set up a new tank and will need to get a grip on the PH behaviour but at present have no way of testing it.
whats the cheapest way of checking (whilst giving useful readings in terms of accuracy) ?
 
It's your low KH that makes it difficult to measure the pH using a probe.
Darrel has an excellent explanation in his post=> http://www.ukaps.org/forum/threads/seneye.31700/#post-363560

There are two options:

1) add Potassium Carbonate or Sodium Carbonate (baking soda) or coral sand or any chalk based hardscape to raise the KH of the tank to around 4-6. This will improve the reliability of the probe's readings.

2) use a reagent based KH test kit.

Cheers,
 
OK, thanks. There's no point having a pH meter if it can't do its job.

So until I can raise the KH, I can only use the drop checker to indicate the CO2 levels?

I've moved the drop checker just above the substrate at the front and it still is yellow.
 
No...No...No...No....

Use the REAGENT from the dropchecker. The DC cannot help you in this exercise.

Cheers,
 
Yeah, I know the DC can't help with a pH profile. I just mean that if I can't get a valid pH profile at the moment, the DC is all I've got to tell me that the CO2 might be sufficient (or maybe not...)
 
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