Deficiency/ferts help please.

PAV331

New Member
Joined
8 Sep 2018
Messages
8
Location
Lincoln
Hi all,

I need a steer in the right direction please.

My tank is nearing 5 months old but has only been running with CO2 for around the past 3 months. I have been dealing with constant diatoms and so have been running it at relatively low light until I see those out (currently at 35% intensity).

My plants are showing signs of deficiency, most notable in the S Repens. This is confusing me as I am dosing 6mls of TNC Complete a day which I thought should be slightly excessive, especially when considering i don’t have a massive amount of fast growers and light is limited. Other symptoms are light surface scum and I’ve just started to notice a small amount of BBA on the root wood. The Salvinia seems to be doing ‘ok’ but not great.

Drop checker is dark green around 20 mins after lights on and I’m fairly confident the flow and distribution is good, almost excessive when the skimmer is on.

Do I really need to add more ferts, or is there something else at work here that I haven't considered?

1. Size of tank. 55ltrs
2. Filtration. Oase Biomaster Thermo 250. Ehiem skimmer as and when needed.
3. Lighting and duration. Twinstar 600E, 6hrs per day.
4. Substrate. Tropica aqua soil
5. Co2 dosing or Non-dosing. Dosing @2bps via inline diffuser
6. Fertilisers used + Ratios. TNC Complete 6mls per day via DD P1 doser, root tabs.
7. Water change regime. 75% every week
8. Anubias, various mosses, Rotala rotundifolia, bucephalandra, Monte Carlo, Rotala H’ra, S.repens and floating Salvinia.
9. Inhabitants. 12 ember tetras, 2 Guppies, 5 Amanos, 3 cherry shrimp, 4 otos.


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Joined
3 Jan 2016
Messages
340
Location
Woking, UK
Drop checker is dark green around 20 mins after lights on
Does the green get lighter during the first couple of hours of light? Ideally you want to reach a light green within the first couple of hours of light, remaining light green throughout the rest of the photoperiod.
 

Zeus.

Member
Joined
1 Oct 2016
Messages
3,108
Location
Yorkshire,UK
Yes it’s light green within 2 hours and green/yellow by lights out.
So you have fluctuation CO2 which is the main cause of nutrient deficiency in CO2 injected tanks due to poor CO2 implementation and/or poor flow.

Your [CO2] must be stable from lights on till CO2 off. Doing a pH profile - take pH of tank water every 30 mins form pre CO2 on every 30 mins till CO2 off. Ideally the pH will drop till lights on till CO2 off. If not them your [CO2] is not stable

We understand that Rubisco's job is to capture CO2 molecules and to deliver the molecules to the Calvin Cycle reaction centers. We know that Rubisco is hugely expensive and consumes a lot of resources to produce and to maintain. In low tech tanks, where the CO2 concentration is low there is a much higher density of Rubisco in the leaf because you need more of the protein to capture the small amounts of CO2. In gas injected tanks, the Rubisco density in the leaf is lower.
we know that when the plant senses that high concentrations of CO2 is available, it responds by reducing the production of expensive Rubisco. When it senses a lower CO2 concentration it must increase Rubisco production, however because this protein is so complicated and heavy, the increased production requires 2-3 weeks in order to change the density in the leaf to match the new gas concentration level. So it is much easier to reduce production than it is to increase production. When increasing gas injection therefore, it hardly takes any time to see an improvement in health. When lowering the concentration, the plant will suffer because it must now ramp up Rubisco production to account for the loss of CO2 availability.

When increasing the light, the plant must reallocate resources from Rubisco production/maintenance in order to deal with the increased radiation. This may entail new pigment production for protection. When the light is reduced, the plant then reallocates the light gathering proteins and can devote them to Rubisco production/maintenance.

So when we mess around with light and gas, we have some degree of predictability.
 

PAV331

New Member
Joined
8 Sep 2018
Messages
8
Location
Lincoln
Thanks for the reply.

So you think it likely that the yellowing seen in my plants is due to poor CO2 implementation? Ok, I can get behind that .

My PH out of the tap is just over 7, and drops to just over 6 by lights on. I’ve found it difficult to get good figures using a liquid test set (can’t determine for sure between 6 and 6.25 and so on), and it only goes down to 6 so I’m not sure how accurate it is around the lower limit. I’ve debated getting a PH pen, but do I really need an expensive one from Hanna Instruments or the likes in order to get reliable results? I don’t mind if it’s a worth while investment.
 

Nick72

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Joined
21 Apr 2020
Messages
283
Location
Kuala Lumpur, Malaysia
Thanks for the reply.

So you think it likely that the yellowing seen in my plants is due to poor CO2 implementation? Ok, I can get behind that .

My PH out of the tap is just over 7, and drops to just over 6 by lights on. I’ve found it difficult to get good figures using a liquid test set (can’t determine for sure between 6 and 6.25 and so on), and it only goes down to 6 so I’m not sure how accurate it is around the lower limit. I’ve debated getting a PH pen, but do I really need an expensive one from Hanna Instruments or the likes in order to get reliable results? I don’t mind if it’s a worth while investment.
I invested in a PH meter around 8 months ago.

I wounded if it was really worth spending 75 pounds on a meter, but I've never looked back.

First I discovered my reading of the PH solution colours was way off, and being able to see the difference between PH6.2 and PH6.8 is just not possible without a pen or meter.

When my tap water became contaminated I immediately saw the PH drop to 5.2, I doubt I would have had a clue if I was using test solutions.

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I now check my tap water PH before every water change.

I've thrown away the PH test solution and the drop checker. I get far more accurate measurements with the PH meter and probe.

So yes, I would get the best PH meter or pen you can find.
 

dw1305

Expert
Joined
7 Apr 2008
Messages
10,187
Location
nr Bath
Hi all,
So you think it likely that the yellowing seen in my plants is due to poor CO2 implementation?
It maybe for the submerged plants, but it definitely looks like there is something else going on. I say this because the Salvinia growth isn't terrible, but it is distinctly sub-optimal and that has access to atmospheric CO2, so it isn't CO2 limited.



Looking at the Salvinia I would try a few more macronutrients, my guess would be that the plants are deficient in one out of nitrogen (N), potassium (K) or magnesium (Mg), probably in that order. Rather than just adding more TNC complete I'd buy some potassium nitrate (KNO3) and "Epsom Salts" (MgSO4.7H2O), they work out a <"lot cheaper in the long run">.

Have a look at the <"dosing calculator"> for the amounts to add.

cheers Darrel
 
Last edited:

PAV331

New Member
Joined
8 Sep 2018
Messages
8
Location
Lincoln
Having paid more attention to the drop checker today, there is definitely room for my CO2 to be cranked up a little. I’ve upped it from 2bps to 2.5 so will see how that goes along with plotting the PH drop the best I can using the test set.

What is more of a concern is that I sat at the tank this morning waiting for the D-D P1 to auto dose, and it didn’t! I’m not sure if it was a one off or if it has been going on for a while. It appears to be set up correctly, and doses on the manual setting fine. I’ll monitor over the next couple of days and see how it goes.

May have to treat myself to a PH meter at some point to. I guess it’s the same as any tool, buy a good quality one and it only hurts once, buy a poor quality one and it hurts every time you use it!

Thanks for your advice thus far.
 
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