Is this a Mg deficiency in my Rotala?

[McGodes1990]

Hi all,

I posted last week but unfortunately didn't get any replies so I thought I'd try again. I've been dealing with this issue for the better part of a year now. My plants are growing at a reasonable rate but are growing unsightly and yellow. I can't figure out what I'm missing but since I run high CO2, have great lighting, good O2, great filtration and circulation, I suspect it's a nutrient deficiency. I've dosed home made EI from GLA salts, Tropica specialized, and now APT Complete and the issue persists. This narrows the issue down to Ca/Mg. I use RO water remineralized with Salty Shrimp GH+ to TDS 150 at water changes. This tank has around 20lbs of Seiryu stone so the GH Kh rises significantly by water change day. Today (Thurs) I got a reading of GH 11 and KH6. I do 50% water changes on Sundays.

I'm wondering if I'm experiencing a Mg deficiency because of the high Ca content leeched by the seiryu and that the Salty Shrimp GH+ is simply adding back not enough Mg? Any thoughts on this? Should I replace the salty shrimp with dissolved Epson salts at water changes instead and just ignore Ca due to the Seiryu? This issue is driving me mad so any insight is godsend. Fortunately algae is virtually nonexistent. Just a little GSA on slower growers.

Here are more details on the tank specs:

The Setup:
UNS 60U (about 19 gallons)
Seiryu Stone
UNS Controsoil (seachem root tabs buried in soil)
Pressurized CO2 (5bps, on 2hr before lights, off 1 hr before lights, lime green by 2 hrs after lights on)
Twinstar 600S LED (8 hour photoperiod: 1 hour ramp up from 0-80%, 6 hrs at 80%, 1 hour ramp down from 80%-0)
Oasebiomaster Thermo 350 filter at max flow.
Temp: 22 celcius

Water:
100% 0 TDS RO Water remineralized with Salty Shrimp GH+ to TDS 150ppm. 50% water changes every Sunday.
Today's GH/KH/TDS: 11dGH/6dKH/212ppm (50% change on Sun)

 

[ceg4048]

I'm wondering if I'm experiencing a Mg deficiency because of the high Ca content leeched by the seiryu and that the Salty Shrimp GH+ is simply adding back not enough Mg? Any thoughts on this? Should I replace the salty shrimp with dissolved Epson salts at water changes instead and just ignore Ca due to the Seiryu? This issue is driving me mad so any insight is godsend. Fortunately algae is virtually nonexistent. Just a little GSA on slower growers.

Hello,
Maybe the paleness is not expressed well in the photos, but really, the tank looks amazing to me.
Paleness can be cause by so many combinations of deficiencies and the cause(s) can differ among the various species. If you are not already adding some Epsom Salt, then just add some and see if there is an improvement. I wouldn't replace anything with it, just add it, give it a few weeks and reassess.
I definitely would not worry about Ca. This is one of Alice's rabbit holes that so many fall into, worrying about ratios of this to that. It's a complete waste of time. Plants will take whatever they want from wherever they can. In aquatic plants there are no nutrients that block other nutrients - that's just is hogwash. For my own part, when I see paleness the first thing I attempt is the macronutrient most responsible for fabricating green chlorophyll, which is Nitrogen. If NO3 doesn't work then it's Iron or Mg -but it could also be any of the other micronutrients so I just add more of the micronutrient mix that has Iron and all the rest in it. There is no need trying to isolate a specific micronutrient.

Cheers,

 

[McGodes1990]

Hey Clive,
Thanks for the reply. The paleness isn't the most egregious I've seen on the internet but it's especially bad on the higher stems in the back. Perhaps more notably, you'll notice that my rotala stems sort of slouch and aren't as tight, upright, and compact as they could be. I'm looking for that tight, vibrant green I've seen in most well cared for tanks like in the pic I've attached below.

I've added a small finger pinch of Epsom salts tonight so I'll observe the plants closely for improvement. I agree, chasing elements is silly. It's just that I've run out of ideas as I've tried dosing 1.5-2x EI in the past to no avail. I was getting readings of 40+ppm Nitrates in the tank during those days, so I eliminated Nitrogen as the culprit.

I would think Salty Shrimp provides all the Ca and Mg my plants need but alas, my rotalas are subpar.

 

[X3NiTH]

The Ratio of Ca:Mg in Salty Shrimp GH+ is 3:1 which is the same as plant tissue, there’s more than enough Mg in there, even with the climbing GH the ratio of Ca:Mg will probably be within normal limits.

I’d say your root tabs have run out of Iron, you have divulged that your NO3 level is not deficient. If the Iron chelate you are dosing for foliar feeding is predominantly EDTA then because of the increasing hardness your pH may be spending a significant time above neutral where the half life for EDTA begins at pH6.5, the chelate starts dropping the Iron leaving the Iron free to react with phosphate and becoming unavailable to the plants (or reduced availability) the effect is also compounded by strong lighting (EDTA is light sensitive as are most Iron chelates).

You likely need to dose an Iron chelate that is more appropriate for this water hardness and pH, for longer term persistence something like DTPA or EDDHA works well, alternatively you can dose more of a shorter term chelate Iron supplement like Ferrous Gluconate which can quickly break down but is highly plant available and full of nutrition, the Gluconate chelate is a fully biodegradable long chain carbon molecule.

🙂

 

[McGodes1990]

Thanks for the detailed response 🙂
Iron was the first culprit I went after over the summer. At the time, I was dosing EI from dry salts and working off the same hypothesis you've proposed, I switched over from GLA EDTA Micromix to the GLA EDTA+DTPA Micromix (GLA EDTA+DTPA Micromix - 1lb (Bag)). Unfortunately, I saw no improvement in plant health. Next, I upped micro dosing to 1.5x and 2x EI. Still no improved plant health. Finally, I added Seachem Flourish Iron (which I believe is Ferrous Gluconate) and still didn't see any results. Those tests eliminated iron as the culprit for me, but I'm willing to experiment more with iron if I missed something in those tests.

I do suspect the tank spends quite a bit of time above a neutral PH. I took an API liquid test today and got a reading of 7.4 just before CO2 kicked on. I always dose first thing in the morning, approx. 2-3 hours before CO2 kicks on so the tank is likely always above neutral when I dose, for whatever it's worth.

 

[X3NiTH]

You’ve covered most things. If you can do one thing differently then I would try dose just before the lights come on when you have a good amount of co2 in the water, that way the plants should be positioned to take best advantage of it. Ferrous Gluconate can last less than an hour in the water depending on factors such as pH, light etc. It’s the only thing I suggest you do differently with the trace elements. I would also say that Calcium has a huge affinity for unbound EDTA so if the Iron gets dropped for any reason there’s no way it can get it back once the Calcium is chelated. DTPA is only slightly better at higher pH, literally at the GH/KH/pH range you have in the tank (I run similar parameters) then DTPA will be degraded by at least 50% in 24hrs, on testing a dose of 0.1mg/L of Ferrous Gluconate and 0.05mg/L of DTPA showed 0.025mg/L the next day, the tank has no way near as much plant mass as yourself, mine are slow growing Buce, yours are mainly fast growing hungry stems.

Have you tested for Iron persistence using a test kit, it’s what I had to do to work out an adequate dosing regime.

🙂

 

[McGodes1990]

I had that same idea about dosing closer to lights-on this morning and started that regime today. I was doing some research last night after you brought up iron, and was digging through some old threads about EDTA vs DTPA vs Gluconate. I found a thread where Tom Barr mentioned that Gluconate is relatively ineffective at higher KH values (3+ if I recall). He said DTPA tends to work best in high KH/pH water. Even though I've dosed that EDTA/DTPA mix in the past, I'm gonna try a DTPA only solution. I ordered the powder from GLA today so I'l begin suplimenting my all-in-one commercial fert with the DTPA solution. To maximize iron usability, I'm gonna dose at 2 hrs past lights-on when the pH reads 6.4 (I took a reading today). The tank starts the day at 7.4 and then works its way to 6.4 and stabilizes for the remainder of the day/night until CO2 off. Correct me if I'm wrong, but in theory this approach should either fix the issue or eliminate Iron as a culprit?

I've never tested iron and I'm not opposed to doing it, but I'm hoping this approach eliminates the need for testing. Since you've dealt with similar conditions, albeit with slower growing plants, I'm curious what the solution was for you? What iron source(s)/dosing technique worked best for you?

 

[Sammy Islam]

I had that same idea about dosing closer to lights-on this morning and started that regime today. I was doing some research last night after you brought up iron, and was digging through some old threads about EDTA vs DTPA vs Gluconate. I found a thread where Tom Barr mentioned that Gluconate is relatively ineffective at higher KH values (3+ if I recall). He said DTPA tends to work best in high KH/pH water. Even though I've dosed that EDTA/DTPA mix in the past, I'm gonna try a DTPA only solution. I ordered the powder from GLA today so I'l begin suplimenting my all-in-one commercial fert with the DTPA solution. To maximize iron usability, I'm gonna dose at 2 hrs past lights-on when the pH reads 6.4 (I took a reading today). The tank starts the day at 7.4 and then works its way to 6.4 and stabilizes for the remainder of the day/night until CO2 off. Correct me if I'm wrong, but in theory this approach should either fix the issue or eliminate Iron as a culprit?

I've never tested iron and I'm not opposed to doing it, but I'm hoping this approach eliminates the need for testing. Since you've dealt with similar conditions, albeit with slower growing plants, I'm curious what the solution was for you? What iron source(s)/dosing technique worked best for you?

Adding FE 2hours after lights on is not a good idea because FE is used within the first 2 hours of the photoperiod. Also the peak of your PH drop should be happening at lights on and should remain stable throughout.

 

[McGodes1990]

Adding FE 2hours after lights on is not a good idea because FE is used within the first 2 hours of the photoperiod. Also the peak of your PH drop should be happening at lights on and should remain stable throughout.

Interesting point, but once I start dosing the DTPA Iron, if I'm following the science correctly, it shouldn't matter when I dose given that the DTPA chelate seems to stay intact up to higher pH values in the 8's? Mine never gets above 7.4.

Until the DTPA arrives I'll try to dose an hour or so after CO2 kicks on. I run it pretty hard at about 5bps so I'll take a reading today 1-1.5 hours after CO2 on and see if I'm at pH 6.4 by then. I suspect I will be. Also, I'm curious if anyone knows what Iron chelate(s) Dennis Wong's APT Complete uses. He's very transparent about what goes into the mix, but I couldn't find any specific info on the iron chelates. The trend with all-in-one comprehensive ferts these days seems to be a combo of DTPA and EDTA, but I'm curious if anyone specifically knows.

 

[Sammy Islam]

Interesting point, but once I start dosing the DTPA Iron, if I'm following the science correctly, it shouldn't matter when I dose given that the DTPA chelate seems to stay intact up to higher pH values in the 8's? Mine never gets above 7.4.

Until the DTPA arrives I'll try to dose an hour or so after CO2 kicks on. I run it pretty hard at about 5bps so I'll take a reading today 1-1.5 hours after CO2 on and see if I'm at pH 6.4 by then. I suspect I will be. Also, I'm curious if anyone knows what Iron chelate(s) Dennis Wong's APT Complete uses. He's very transparent about what goes into the mix, but I couldn't find any specific info on the iron chelates. The trend with all-in-one comprehensive ferts these days seems to be a combo of DTPA and EDTA, but I'm curious if anyone specifically knows.

I dose my micros as soon as my PH drop allows my DTPA to stay chelated, so an hour after CO2 turns on. My lights turn on after 2 hours of CO2 when i have achieved my targetted PH drop which stays stable during the photoperiod, drop checker very lime green at lights on.

Also not a good idea to dose FE during the photoperiod as the chelates are light sensetive and degrade, so you want to keep FE available for when it's needed most. I think EDTA starts breaking down around PH6.5 and DTPA around PH7.4.

 

[McGodes1990]

I dose my micros as soon as my PH drop allows my DTPA to stay chelated, so an hour after CO2 turns on. My lights turn on after 2 hours of CO2 when i have achieved my targetted PH drop which stays stable during the photoperiod, drop checker very lime green at lights on.

Also not a good idea to dose FE during the photoperiod as the chelates are light sensetive and degrade, so you want to keep FE available for when it's needed most. I think EDTA starts breaking down around PH6.5 and DTPA around PH7.4.

Gotcha, ok my CO2/photoperiod relationship is about the same as yours. Though I do have a 1 hr ramp up in lighting for my Twinstar from 0% to 80%. I can always do away with that ramp up to cut down on light degradation of the iron chelate.

CO2 is on at 11:00am and lights ramp up up from 12:30-1:30pm. So I would in theory be dosing around 12:30pm, 1.5 hours after CO2 kicks on.

 

[Sammy Islam]

Gotcha, ok my CO2/photoperiod relationship is about the same as yours. Though I do have a 1 hr ramp up in lighting for my Twinstar from 0% to 80%. I can always do away with that ramp up to cut down on light degradation of the iron chelate.

CO2 is on at 11:00am and lights ramp up up from 12:30-1:30pm. So I would in theory be dosing around 12:30pm, 1.5 hours after CO2 kicks on.

Ideally you would dose before the lights come on, the ramp up doesn't matter as the ferts should be available for the first couple of hours when the plants need them the most. The first half of the photoperiod is most important in terms of CO2 and ferts.

If your target PH is 6.4, then you want want to be hitting PH6.4 when the lights turn on and it should remain stable for the rest of the photoperiod.