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Need help / advise on calculating ferts

timseren

New Member
Joined
4 Jan 2022
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14
Location
Lithuania
So it's almost a year now I cant get my new tank to have good plant grow. First I thought it was not enough flow, so installed another filter, then thought maybe diffusor is too small, so added in-line style. Last resort was to change co2 regulator and instead of turning off at night, I've made a constant co2 flow. Nothing yet helped, and looking at new fast growing (and older as well) plants, I can clealry see that something is missing from fertilizers. I am not great at math, so maybe my calculations are just wrong and I am dosing not enough / too much. Advise would be really welcomed.

Tank - 90p (90 x 45 x 45) 1year and 7month old.
Lighting - Twinstar SM III (60% of power)
Filter - Oase 850 thermo; Eheim eXperience
Substrate: Tropica
CO2: 24/7 through in line diffusor (green drop checker)
Dosing philosofy: Estimated Index
Water change: 60-70% weekly
Fertilizers: Aqua rebell Estimated Index; Aqua rebell Eisen. / daily with dosing pump

Let's look at the numbers, as Aqua rebell claims:

1 ml Makro Basic Estimative Index per 40 litres of tank water adds the following nutrients:

NO3 0.92 mg/l
PO4 0.17 mg/l
K 0.70 mg/l

and recomends to add 5ml per 40liters, which should be in "golden zone" for EI target levels per my calculations per day:

NO3 4.6 mg/l
PO4 0.85 mg/l
K 3.5 mg/l

Dosing 7 times per week (5ml per 40ltr) this should be in total of:

NO3 32.2 mg/l
PO4 5.95 mg/l
K 24.5 mg/l

As my tank is 180liters, I've calculated I need to add daily 22ml macros to reach targeted levels above. The only issue is maybe a little too high PO4 level?

Regardin micro, as per Aqua rebell information, 10 ml Mikro Basic Eisenvolldünger per 100 litres of water add the following nutrients:
Fe 0.10 mg/l
As my target is 0.4mg/l, so I'm adding 4 times the dose, 40ml per 100 liters of water per week or 90ml per 180 liters.

As of the problems in the tank, main issue is the lack of growth in all the plants, especially the quicker ones like Myrophyllum mattogrossense. These are getting really pale, yellowish and even whitish. There are alot of GSA (green spot algae on the glass, sadly quite a lot of BBA, and some GBA.
 
First thing I'll ask is for a picture. Sometimes pictures say a thousand words.

CO2: 24/7 through in line diffusor (green drop checker)
This is not required. Plants do not require CO2 when lights are off. I would simply open CO2 1-2 hours before lights go on and turn off CO2 1 hours prior lights go off making sure you have a stable CO2 concentration in the water throughout the photoperiod. You can aim for 1 PH drop. I suggest reading this for more information on how to tweak your CO2: Dialling in the CO2 injection Rate and CO2 Profiles

Lighting - Twinstar SM III (60% of power)
Dosing philosofy: Estimated Index
Fertilizers: Aqua rebell Estimated Index; Aqua rebell Eisen. / daily with dosing pump
Dosing 7 times per week (5ml per 40ltr) this should be in total of:

NO3 32.2 mg/l
PO4 5.95 mg/l
K 24.5 mg/l
The moderate amount of light you are pushing does not justify the use of such high macro levels. You could easily cut that in half. But again a picture of your tank would help in assessing what the problem really is.

As of the problems in the tank, main issue is the lack of growth in all the plants, especially the quicker ones like Myrophyllum mattogrossense. These are getting really pale, yellowish and even whitish.
Clearly the amount of fertilizer here is not the problem considering how much you are dosing. You have not mentioned anything about the water you are using. RO? TAP? If Tap what is the GH/KH of that water?

There are alot of GSA (green spot algae on the glass, sadly quite a lot of BBA, and some GBA.
This leads me to think you have CO2/light not dialed in properly.
 
Hi all,
First thing I'll ask is for a picture. Sometimes pictures say a thousand words.
Certainly does.
As of the problems in the tank, main issue is the lack of growth in all the plants, especially the quicker ones like Myrophyllum mattogrossense. These are getting really pale, yellowish and even whitish.
Which leaves? Have a look at <"Duckweed Index says Nitrogen please?"> and <"Should i start to fertilize?">.

cheers Darrel
 
Thanks for suggestions. I'll look into the links provided. Water is TAP water (zero problems with previous tanks). Light period is 7 hours. Pictures are below:

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Here is what I see.
main issue is the lack of growth in all the plants
1. Your tank is virtually planted with 100% slow growing plants which does not justify the use EI dosing.

2. All these algae and specially BBA you are seeing is only going to get worse if you don't up your game in terms of maintenance. I see quite a lot of dust on the substrate. I would try to do superficial vaccums at each water change to remove as much as possible decomposing matter. Do not let this dust get scattered in the water column. You could also do some spot treatment with hydrogen peroxide on some of the most affected plants and hardscape to remove as much as possible the BBA. For more sensitive plants I recommend you simply trim them.

Tap water is quite hard, last I checked it was 7KH and 11GH. Micro fertilizer I dose has these:
3. and this is why I asked about whether you used RO or TAP and your GH/KH. Your KH is high which also bring your PH up. Which in turn could generated some nutrients unavailabilities. You are dosing Aqua Rebell Mikro Basic Eisen which uses 3 types of chelated iron. HEDTA, EDTA and DTPA. The first two are not really suitable for higher KH/PH. Specially HEDTA. DTPA could withstand higher PH but in your situation I would dose a mix a of DTPA and HEDDTA. This is most probably why you are seeing what seems to be Fe deficiencies in your Myrophyllum. At the highest recommended dose Aqua Rebell Mikro Basic Eisen is only providing 0.14ppm of Fe, which could work with soft water but not in hard water. Most of what you add is probably unavailable due to your higher KH/PH.
If you can, try to mix TAP water with RO water or rain water in order to decrease your KH. This should improve your tank condition. If you can't then I would suggest dosing some EDDHA instead along your Mikro Basic Eisen. EDDHA will tint your water pink if you dose too much so be conservative here. I would also decrease the overall amount of ferts you are dosing. It's unnecessary in such tank setup. You don't really have fast growing plants, your light intensity is in the medium zone and your CO2 levels are what seem to be low considering the color of your drop checker.

Do you know how hard and alkaline (dGH and dKH) your tap water is? and do you add any magnesium (Mg)?
Tap water is quite hard, last I checked it was 7KH and 11GH.
Your Mg is currently at ~0.9ppm/week from macro side + ~0.5ppm/week from micros side. That's ~1.4ppm/week + the additional Mg that comes from your TAP which is probably a big chunk. I am not convinced this is an issue. Levels looks fine to me.
Screen Shot 2023-09-20 at 07.57.32.jpg

Water is TAP water (zero problems with previous tanks)
This does not mean much. Not two tanks are the same even in your house with the same water. Soil, hardscape, flow, CO2, light...all play a role in making each tank different.
 
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Thanks guys! I clearly saw that something is missing but upscaled the wrong fertilizer. Cut the macro dose in two and increased micros. Also removed quite a lot of ferns as they were quite crowdy, roots decaing so indeed quite a lot of debree and worse water flow. Will increase water changes and soil syphoning. Fingers crossed!
 
Agree with what others say here. Your Myrophyllum mattogrossense does look suspect for iron deficiency, and that ties in with your GH & KH readings. If things do not improve with your increased micro dose, then as @Hanuman states, use some strong Iron Chelates. I have iron issues and have to dose DTPA & EDDHA, otherwise my plants with go white.

I also had uncontrollable amounts of BBA, but once I sorted out the deficiency and also tackled any organic waste, my BBA was under control. Have a look at the 2Hraquarist website article on siphoning & maintaining your substrate
 
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