Black Brush Algae (BBA) and CO2

[Sleepy_lancs]

Hi All,

I am still fighting my war with BBA. Yeap.. its killing my interest. Anyway, lets see what can come out of this. Flaming isn't welcome.

Tank Dimensions (LxWxH, specify units): 4 ft x 2 ft x 2ft

Lighting Intensity(No of Watts) : 220 watts
Number and type of Lighting (FL/PL/MH) : 55watts PL x 4
Age of light bulbs : 1 mth old
No. of hours your lights are on : 10 hours

CO2 Injection Rate (bps) : uncountable.
Type of CO2 (DIY/Cylinder) : Cylinder
Method of Injection (e.g. Diffusor/Reactor) : Reactor

Liquid fertilisers Used (Product name. E.g. Seachem Flourish) : KNO3, KH2P04 and LushGro Rexolin (FE and trace) (from Malick)
Fertilization regime (Frequency and amount per dose) : 3 times a week
N03 = 6.6ppm per dose (19.8ppm per week)
KH2PO4 = 1.32ppm per dose (3.96 per week)
Fe = about 0.084 ppm per dose (0.252 per week)

Other fertilisers (Product name. E.g. Root Monster) : Some under the crypts

Other additives (Product name. E.g. Seachem Prime) :
Seachem EQ. Weekly 1 TSP

Type of Filter (overhead/internal/canister, Product name/model if possible) : Ehiem 2028 Canister
When was the filter last washed : 2 mth
Filter media used : Assorted. Mainly Angel Bio something
When was the media last changed : NA
What was changed : NA

Age of setup (i.e. since initial setup or last major re-do ) : 2 mths

Water change frequency : weekly
Amount changed : 25%

Water surface movement (None/gentle/turbulent) : gentle due to fan to reduce heat
Circulation (None/gentle/turbulent) : gentle

Tank Temperature : btw 28-30

Chemical Properties (Fill what you can)
-------------------------------------
KH (dKH): 4
GH (dGH): Not sure
pH : 6.4
NH4 (ppm): 0
NO2 (ppm): 0
NO3 (ppm): Not sure
PO4 (ppm): Not sure
Fe (ppm): Not sure

Bioload (Number and type of fish and plants)
------------------------------------------
- Yamotoes Shrimps x 50
- Otos x 50
- Crypts Mostly
- Java Fern (1/8 of tank)

Describe your problem :
----------------------
BBA infected on plants near water outlet . Aways near where CO2 get injected first. No matter I did, it will keep coming back. I dropped PH to 6.2 and still it grows. Sigh.

I was about to try not changing water just water top up. Since adding new water means I add Baking Soda which could be inaccurate (registering about btw 4 KH - 4.5 KH). Comments are welcome.

[PeterGwee]

Take a 500ml sample of your tank water and let it sit for 24-48hrs. Measure the pH of the sample after the 24-48hrs. Drop the pH of the sample after 24-48hrs by 1.0 pH to get ~30ppm. If your CO2 is good, all that is left is circulation. As plant mass increases, it can impede circulation to a certain degree and requires a possible change in flow pattern to overcome the issue. The prandtl layer issue is very real.

Regards
Peter Gwee

[Sleepy_lancs]

Hi PeterGwee,

I don't quite understand this "Drop the pH of the sample after 24-48hrs by 1.0 pH to get ~30ppm." Care to elaborate?

[PeterGwee]

Eg. 500ml of tank water as sample that sits for 24-48hrs without CO2 injection. pH of sample after sitting for 24-48hrs is say 7.6.
Drop the pH 7.6 down by 1.0 (6.6) to get an approximate CO2 of 30ppm.

Or try the following method by Tom Barr.

At issue is the measurement of CO2 pm without relying on KH on the tap or the tank(How many here have reported 200ppm CO2 and healthy fish plants? Or whining about ADA As and not being able to measure CO2-generally from those who are not using ADA AS :-) ?).

I'm no fan of the equation for the hobbyists, but it does work.
But I'm not suggesting folks do that unless they are all into that.

I just make a simple ref solution. DI water and a KH of 1.
Then take the tank sample.

Wait 48 hours, measure the difference in pH.
I make an assumption: the partial pressures of CO2 will be the same for both samples.

That is a reasonable assumption.

Any reduction of the pH in the tank sample is then assumed not to be due to CO2 gas. also, a reasonable assumption.

So say the difference between the tank and ref sample is .5 pH units.
You can look on the pH/KH chart and see what the reduction in pH will be required.

So say the pH/KH of the ref solution is:
7.8 pH/KH= 1 and you need to add enough CO2 to get 30ppm which will be about 6.0 pH.

7.8 is the ref sample and the tank sample measures at 7.3 pH.

7.3-1.8 = 5.5 pH is your targeted pH for 30ppm.


That's it which is a simple method to get around things like whacky KH issues and 100-200ppm supposed CO2 readings, ADA or peat based reductions that skew the pH/KH table.

If the pH KH works well for you, stick with it, this is for folks havign troubles with that method and still want to measure the CO2.
1. Make sure to top off with DI water for the ref smaple and tank sample after 48 hours , evaporational losses will influence things, also use a good size sample, say 500mls, not 5mls which will be entirely evaporated after 2 days in many places.

There is also another method I use to measure CO2 in tanks with no KH at all.
It relies on another assumption, the CO2 ppm addition rate is the same between making a tank have a KH= 1 and then do a water change/s soon thereafter and knock the KH down to zero or very close it. The CO2 ppm injection rate and rate of plant uptake will be the same in both cases, you just will not be able to measure the pH/KH once the KH goes to zero, but this is a indirect method also and gets around the measuring need for KH for the actual Planted tank itself and relies on ref sampling, either for test or use the entire tank for the reference.

It's just an alternative method to avoid some pitfalls folks are now recently realizing, but uses the pH/KH method as a back up reference still.

I'm not a fan of tweaking the fish to the surface, then backing off a tad for a method. Many do it, but there's something none too ethical about it either.

Anyway, I wanted to know what the CO2 was or at least pretty close and the many folks on these forums that report 100-200ppm of cO2 ands healthy fish, used pH calibrated probes, good KH test kits etc and the folks still have issues unrelated to tannins, namely from non carbonate alkalinity I'd suspect, can figure a way around this as well as folks running no KH tanks.

It's certainly not nearly as hard nor as confusing as it sounds, much like making a CO2 reactor.

Regards,
Tom Barr

Regards
Peter Gwee

[Sleepy_lancs]

Ah.. Okay.. Will post the finding at 0200 hours.. which is 24 hours after 500 ml was taken out this morning

[neon]

Eg. 500ml of tank water as sample that sits for 24-48hrs without CO2 injection. pH of sample after sitting for 24-48hrs is say 7.6.
Drop the pH 7.6 down by 1.0 (6.6) to get an approximate CO2 of 30ppm.

Or try the following method by Tom Barr.



Regards
Peter Gwee

Peter,

With this explanation , now I understand the CO2 PPM calculation in my tank water condition.

Now, need to work on the CO2 diffusor/reactor again. As mentioned, I tried all the reactors/rainbar method, Co2 catch time still no good . What is your suggestion to improve this ?

Thanks !

[PeterGwee]

Peter,

With this explanation , now I understand the CO2 PPM calculation in my tank water condition.

Now, need to work on the CO2 diffusor/reactor again. As mentioned, I tried all the reactors/rainbar method, Co2 catch time still no good . What is your suggestion to improve this ?

Thanks !

Basically more flow throughout the tank to mix the CO2 well. You can use multiple diffusers since its a large tank at different parts of the tank and place them near strong currents so that the mist moves around the tank well. Its all about the flow rate once the CO2 rate is dial in.

Regards
Peter Gwee

[Sleepy_lancs]

After 24 hours. The PH now is standing at 7.7. But I am not sure how to read that against Tom Barr's explaination. Does it mean I should hit PH = 6.7? If so.. I am well below it. Why would I still have BBA from the place where co2 is expel? Its a major puzzle. My tank has a external Eheim powerhead driving the co2 reactor. Reactor is from NA which is a water filter refitted as a co2 reactor. The outlets is position to cover the entire tank. Plants that are affected are those near the co2 enriched outlet. Does it mean I should turn the reactor off if there isn't any co2 injection during off light hours? Any lights to shed for this "blind" person?

[Sleepy_lancs]

After 48 hours, PH = 8.0.

[juggler]

Peter: For Sleepy_lancs's case, is the below calculation correct using the example given by Tom Barr?

Ref sampe 8 pH/ 4 kH need to be reduced by 1.4 to 6.6 pH to get 30ppm CO2, using a CO2/kH/pH relation table.
Tank sample is 6.4 pH.
So 6.4 - 1.4 = 5 pH is the target pH for 30ppm CO2?

[PeterGwee]

Peter: For Sleepy_lancs's case, is the below calculation correct using the example given by Tom Barr?

Ref sampe 8 pH/ 4 kH need to be reduced by 1.4 to 6.6 pH to get 30ppm CO2, using a CO2/kH/pH relation table.
Tank sample is 6.4 pH.
So 6.4 - 1.4 = 5 pH is the target pH for 30ppm CO2?

KF, Sleepy_lancs is not doing Tom's method since I don't see the ref sample. But, the example shown by you is right if that is the case. DI water is pretty easy to get in supermarkets.

The other thing is he needs to make sure to top off the evaporated water using DI water to maintain the sample quantity. (The baking soda does not evaporate and if the water sample volume were to drop, you would notice an increase in KH and thus pH over time.)

Regards
Peter Gwee

[Sleepy_lancs]

Errr... I am lost... care to explain with reference to my reply??

I must hit PH 5.0???

[dc88]

I suspect Sleepy_lancs' case could be the type of plant mass : "Crypts Mostly, Java Fern (1/8 of tank)". At 1.8 wpg with slow growth plants such as crypts and ferns how much nutrient the plant can consume ? Plus weekly 25% water change may not be enough to reset the water condition. So at the weekly dosing rate of 20ppm NO3 and 4ppm PO4 these will accumulate.
Noted the successful crypt and fern tanks we saw on the forum are mostly non-CO2 ? I would suggest to cut the fert to once a week and stop the CO2 for a crypt/fern only tank; or to add in more fast growth plants if with current fert and CO2 regime.

[PeterGwee]

Errr... I am lost... care to explain with reference to my reply??

I must hit PH 5.0???

Get some De-ionized water and then add baking soda to raise it to about 1dKH and etc. Use it as a reference sample along with the tank water sample. Let both sample sit out for 48hrs and make sure that both water sample have the same volume as started after 48hrs (top off with DI water...shouldn't be a huge difference if the sample is large enough.).

The whole purpose of this new measurement method is to get close enough to the exact amount of CO2 in the tank. You still need to move the CO2 enriched water around to the plant leaves in order for them to uptake. Larger tanks have circulation issues if measurement is in order.

If you do CO2 24/7, you would see that the CO2 level actually drops throughout the day due to uptake as the rate added is slower (you cannot add too much or else you would overdose during the night where there is no uptake. New tanks usually don't see that issue fast since plant mass/health are not at the peak and uptake rate is slower.)

Regards
Peter Gwee

[valice]

In supermarkets, where will the De-ionised water be?

[PeterGwee]

I suspect Sleepy_lancs' case could be the type of plant mass : "Crypts Mostly, Java Fern (1/8 of tank)". At 1.8 wpg with slow growth plants such as crypts and ferns how much nutrient the plant can consume ? Plus weekly 25% water change may not be enough to reset the water condition. So at the weekly dosing rate of 20ppm NO3 and 4ppm PO4 these will accumulate.
Noted the successful crypt and fern tanks we saw on the forum are mostly non-CO2 ? I would suggest to cut the fert to once a week and stop the CO2 for a crypt/fern only tank; or to add in more fast growth plants if with current fert and CO2 regime.

Yup, once a week after the water change is enough for the ferts likely and perharps 2x a week if the growth is great.

No, lots of folks have done well with CO2 enriched crypt tanks. Learning to use CO2 well is sometimes a tough learning curve. Its sort of a daily affair from what I can see. Uptake does vary over time due to increase or decrease in plant mass. You might miss sometime and by the time you test it doesn't show.

Regards
Peter Gwee

[PeterGwee]

In supermarkets, where will the De-ionised water be?

Distilled water.....

Regards
Peter Gwee

[vincentlii]

I think calcium is missing from your fertilliser. Did u recycle the gravel from another tank or using new gravel?

[valice]

Seachem Equilibrium is his source of calcium...

[Sleepy_lancs]

Get some De-ionized water and then add baking soda to raise it to about 1dKH and etc. Use it as a reference sample along with the tank water sample. Let both sample sit out for 48hrs and make sure that both water sample have the same volume as started after 48hrs (top off with DI water...shouldn't be a huge difference if the sample is large enough.).

The whole purpose of this new measurement method is to get close enough to the exact amount of CO2 in the tank. You still need to move the CO2 enriched water around to the plant leaves in order for them to uptake. Larger tanks have circulation issues if measurement is in order.

If you do CO2 24/7, you would see that the CO2 level actually drops throughout the day due to uptake as the rate added is slower (you cannot add too much or else you would overdose during the night where there is no uptake. New tanks usually don't see that issue fast since plant mass/health are not at the peak and uptake rate is slower.)

Regards
Peter Gwee

Hi Peter,

If I get your answer correct, that would be reference solution is 1 dKH while my tank water is at 4 dKH. And I let both sit out for 48 hours. Is that right?

I don't do 24/7. I have the CO2 on timer with the lights. I don't think circulation is a problem... Perhaps I should attached a picture for easy reference.