Water parameters

[Wong Chun Kit]

Hi people. I have a few questions to ask.

Recently I tested my water parameters.

NO3: 10-15
PO4: 0-0.03
Gh: 3-4
Ph: 6.5 - 7.0
Kh: 3-5
Temperature: 26-26.5 degree Celsius
Light hour: 8 hours
2x t5ho 4ft

Ei dosing, but haven't been doing so for awhile. Not sure if it is required.

1. Do you guys add baking soda during water change? A few weeks ago I tested my water and kh was 0. So I added baking soda to raise it to 5. But within 2 days the kh dropped to 3. Is it ok?

2. How does the relationship of kh ph and co2 work? From the table do I just compare and make sure it falls in the right range?

3. Is my water parameter ok? I think my potassium is 0 because I don't know if it is important to dose.

4. My tank is quite heavily planted, and so far most plants are growing well, though sometimes there are algae growth, on my annubia, fern and glandulosa. My pinnatifida sometimes have black spots on the leaves, and repens have never succeeded.

Will appreciate any kind responses and advice!


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[Urban Aquaria]

1. Do you guys add baking soda during water change? A few weeks ago I tested my water and kh was 0. So I added baking soda to raise it to 5. But within 2 days the kh dropped to 3. Is it ok?

What substrate are you using? Active soil like ADA Amazonia Aquasoil?

If you are using active soil, it will naturally pull down KH to 0 so that it can buffer the lower pH for you. In such cases, the soil will control the KH and pH for you. Don't add other stuff like baking soda to buffer up the KH again as it will be counterproductive (ie. constantly "fighting" against the soil characteristic) and may exhaust the buffering ability of the soil much quicker.

2. How does the relationship of kh ph and co2 work? From the table do I just compare and make sure it falls in the right range?

The kH and pH relation chart for measuring Co2 levels only works if your tank water is not buffered by other stuff like soil or additives... if there are external buffers controlling those 2 parameters, the chart will not be valid.

For those who keep planted tanks using active soil substrates, they will have to use a drop checker which contains Co2 indicator solution (containing known KH 4 and pH 7.0 values) to do the measurement. The indicator solution inside the drop checker is separated from the tank water by an air gap and not buffered by external sources, so any changes in its parameters and indicator color will reflect the correct Co2 levels.

3. Is my water parameter ok? I think my potassium is 0 because I don't know if it is important to dose.

Your parameters look okay, water temp is nice and cool. I guess you are running a chiller or air-con in the room?

Potassium is an important macro nutrient for plants, it does tend to get used up quickly which in turn limits their uptake of other nutrients and results in plants experiencing nutrient deficiencies. If you find that potassium levels are getting low or deficient, just dose more of it as required.

4. My tank is quite heavily planted, and so far most plants are growing well, though sometimes there are algae growth, on my annubia, fern and glandulosa. My pinnatifida sometimes have black spots on the leaves, and repens have never succeeded.

Yeah, you will just have to manually remove as much algae as you can, trim off all leaves that are not healthy or melting (those will not recover anyways). That will help encourage growth of new healthy leaves.

Add in a combination of algae eaters to help manage the algae, like shrimps, otos, nerite snails etc. Each of those algae eaters specialize in different types of algae, so keeping a combination of them will enable more efficient management of the various common algae that occur in planted tanks.

[kaen130]

Hi, let me share what I learnt from the gurus here.

To Qns1:
Do U keep sensitive live stock that is vulnerable to pH fluctuation? If not, based on my own opinion, it is not necessary. I'm keeping CRS in planted tank with CO2, I nvr add baking soda during water change.

Qns 2:
I learnt from the gurus here that high KH will prevent pH swing too much when u start CO2 injection and stop CO2.
For example, if u want to achieve 30ppm of CO2:
- If ur KH is 3 and pH is 6.8 before CO2 start, pH will drop to 6.5 and u have 30ppm of CO2 in ur aquarium
- If ur KH is 1, pH will have to drop to 6.0 to have 30ppm of CO2 in ur aquarium.

In summary, higher KH will prevent pH swing.

To ur Qns 4:
I'm not expert enough to answer all here. But I can share my experience with S.Repens, initially it will melt due to root not established. It took a while for my S.Repens to look fine. I was quite paranoid initially too, but I quite it is normal=)


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[Wong Chun Kit]

@urban aquaria
Thanks for your advice! Never knew Ada soil could buffer. But one thing that troubles me is the amount of CO2 I had to pump.

Before I had kh up, the drop per second is insane for my drop checker (which I use standard kh4) to turn green. But it seems that after I up the kh in my tank, I can have less bubble per second (around 3-4 per sec). Not sure if it makes sense. Didn't change the pump placement or anything.

So I suddenly had this false sense of achievement. Haha. I use an inline atomizer.

And yes I run a chiller! Though not very sure if it really helps my plants grow better.

I'm just thinking how much potassium is enough. There was a time when I follow the ei dosing diligently. And there was a bba outbreak. So I'm skeptical about dosing. The only think I add consistently now is flourish.

Yup have Amano and sae to help out, maybe should look at snails.

@kaen130
Thanks! But does it mean the higher kh, the lesser co2 I need to pump?

Yea I have tried growing a lot of plants before, repens seems to give me a lot of problems. It will completely melt and die off. Maybe there is no affinity. Haha.


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[kaen130]

@kaen130
Thanks! But does it mean the higher kh, the lesser co2 I need to pump?

Yea I have tried growing a lot of plants before, repens seems to give me a lot of problems. It will completely melt and die off. Maybe there is no affinity. Haha.

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Yes high KH lesser CO2 to pump. KH measure the carbonate in the water. Example, soft drinks has super high KH because of the gas. Carbonate itself is CO3, so plant can extract the carbon from water itself.

Previously I tried to add, and it is quite a hassle trying to control the KH to be around 4-5...sometimes I got too much, sometimes I got too little...so I gave up.

But like UA mentioned (he is also one of my sifu here), it is unnecessary to add Baking Soda if u use Aquasoil. So far so good for my tank . Most impt is a stable amount CO2 injection to prevent algae outbreak. I find playing around with CO2 level will cause algae to appear, let it stabilize and trim away affected leaves.

As for S.Repens, do give it a try again, once strong roots form, everything will be ok

And don't miss out Potassium, it is an impt source of fert for plant, go google about potassium deficiency to see what will happen if not enough of it


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[Xiaozhuang]

Yes high KH lesser CO2 to pump. KH measure the carbonate in the water. Example, soft drinks has super high KH because of the gas. Carbonate itself is CO3, so plant can extract the carbon from water itself.


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This part is not entirely true; most plants do not preferentially uptake carbonates as it is very energy intensive to do so; having higher KH doesn't mean you need to inject less CO2.
Read the link: http://www.barrreport.com/forum/barr...function-of-kh

[kaen130]

This part is not entirely true; most plants do not preferentially uptake carbonates as it is very energy intensive to do so; having higher KH doesn't mean you need to inject less CO2.
Read the link: http://www.barrreport.com/forum/barr...function-of-kh

Thanks Xiaozhuang for pointing out what I had been understanding wrongly.

Just to clarify further, so if I inject the same amount of CO2 into 2 different aquarium with different KH, the pH will end up different (i.e. Lower KH Lower pH and Higher KH Higher pH)?


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[Xiaozhuang]

Yup, but the CO2 available to the plants is the same. (as far as aquarists are concerned). The only difference is the pH change as you stated. i.e. pH falls less per unit of CO2 the higher the KH.

[Wong Chun Kit]

Ok I understand now.

But I thought it was chemically sound, (A level chemistry sound) since the reaction is reversible.

CO2 + H20 <-> H+(hydrogen ion) + HCO3- (bicarbonate)

And by Le Chatelier's Principle, the addition of bicarbonate will shift the reaction in favor of CO2.

Haha. But I guess experience matters more here so we will just leave it as it is. Thanks for the discussion!


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[Xiaozhuang]

only 1 out of 400 molecules of the CO2 actually form carbonic acid, the remaining 399 stay as CO2[aq]. Very little CO2 is actually "absorbed" due to the alkalinity. A pH/KH of say 6.0/ 1.0 dKH vs say 7.0/10.0 dKH takes about the same amount of CO2 to hit 30ppm, since as mentioned, most of the CO2 is still in the CO2[aq] form. The alkaline KH water will hold more Total dissolved Carbon, but they still hold the same CO2[aq] ppms. ~ more details in the barr-report link.