Help understanding Seachem fertilisers - The Planted Tank Forum
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post #1 of 6 (permalink) Old 08-24-2020, 02:35 PM Thread Starter
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Question Help understanding Seachem fertilisers

Dear All,

Looking to understand better how I am fertilising my 45 litre planted tank. There's no problem, actually everything is going rather nicely at the moment (touch driftwood!), but this is more by luck than a complete understanding of what I'm doing. Would appreciate any insights, guidance, links to useful reading material, etc, please!

Tank is 45 litre, Amazonia substrate, Kessil A360X light, pressurised CO2, light fish load (5 zebra danio, 6 cardinal tetra, 2 nerites, 4 amano shrimp), external Fluval 207 canister filter, established about 6 months ago and all seems pretty happy and stable.

Plants are all fairly low demanding I think:
- lots of Christmas moss blanketing driftwood
- java ferns
- eliocharis pusilla grass
- floating salvinia currently covering half tank surface
Heavily planted in terms of minimal substrate visible, but no demanding stem plants etc of any sort.

My goal is to have a lush green tank where the plants are all healthy, but that doesn't need a massive amount of constant plant trimming and maintenance. This is what I currently have, algae in retreat for now, all looking great, tank seems in balance and taking care of itself without too much interference, critters happy, kids love it, enough maintenance required for relaxed pottering after kids asleep but not too demanding

I fertilise with full Seachem range except for Excel and Advance (so Flourish, Trace, N, P, K and iron) based on Seachem's suggested weekly dosing schedule. Tank started off with soft tap water, now using RO water, always remineralised to 7GH with Equilibrium. Initially I assumed that Seachem's dosing must be based on a heavily planted tank with demanding plants so I dosed at 50% of their recommendations thinking this might still be too much. But whenever I tested the tank water, nitrate and phosphate were both zero.

So I upped dosing to 100% recommended dose. Plants maybe looked a bit better but still zero nitrate and phosphorous measured in the tank water. I test with API liquid test kits, and I've checked that they are working properly by making up reference solutions with respective fert's in plain RO water. I have now upped the dosing to 200% of Seachems recommended "beginner" dose for N, P and K (still at 100% for Flouorish, Trace and iron), but still no nitrate or phosphate at the end of the week before a water change.

I don't see any sign of deficiency, but I'm also aware that apart from the blaringly obvious, I'm not at all experienced at this! All the plants are lush green, which is what I wanted. So everything seems good and I don't think I need to change anything. But, I have these questions:

1) Should there not be some leftover nitrate and phosphate in the water column at the end of the week before I do a water change? Occasionally I might see a hint of nitrate, but usually zero and never the slightest sign of phosphate (although the API test kit doesn't have much resolution at the low end).

2) If there is no trace of nitrate and phosphate in the water column, does this mean that I am limiting the plants? (Actually I don't want them to grow any faster because I don't want to have to do more maintenance and everything looks good as is, but just to understand what's going on).

3) I probably don't need to dose iron (no red leaf or stem plants), but thought might as well buy in to the whole Seachem lineup from day one...

4) I don't have a potassium test kit so have no idea of the level in the tank. I dose nitrogen, phosphorous and potassium all at 200% of the Seachem recommended beginners dose assuming that the strength of the 3 products already takes into account the typical ratio in which they are required by plants. So I'm assuming that there is also no potassium in the water column by the end of the week - is that a safe / sensible assumption to make?

5) If I wanted maximum plant growth (which I don't!), would I increase the NPK dosing to 300%, 400%, 500% of Seachem's beginner dose until I consistently see leftover nutrients in the water column just before the water change?

6) It seems that the salvinia I have floating on the surface really sucks up nitrates (other fert's too?) from the water. Is this why I never seem to see any nitrate or phosphate in the tests? This was the plant that I noticed the biggest increase in growth in when I upped the NPK dosing from 100 to 200%. I guess it sucks up whatever the water column offers, but then am I limiting the other plants if the floating salvinia is stealing everything? (I use this tank to grow it for my other shrimp tanks where the critters like to munch holes in it and where it doesn't grow so lushly due to lack of light, CO2 and lower fert's).

Ok, so hopefully that kind of explains where I'm at in my understanding and learning. Have I got anything wrong, misunderstood or plain missed something? All guidance gratefully received!

Just to note:
- I want to stick with Seachem fert's line due to ease of sourcing here in Singapore, and my tanks are small so cost is not an issue as I don't use that much
- I have no interest in mixing my own fert's and can't easily access dry powders here. I'm happy for Mr Seachem to do all that and sell it to me in a nice bottle.
- IE dosing doesn't appeal to the engineer in me that likes measurement, precision and exactness. Just adding way more than the plants will ever never makes sense when you want to maximise growth, but I would prefer to learn enough to be able to dose what my plants actually need and be able to maybe hold them back slightly at peak health to minimise maintenance
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post #2 of 6 (permalink) Old 08-24-2020, 06:21 PM
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1: There might be some leftover but in my opinion you shouldn't target for excess just to prevent algae outbreak

2: I wouldn't think so. Since those are both fertilizers, limiting them will(mostly) simply slow plant growth

3: I would agree that you probably don't need iron at this time

4: It's hard to really say, but dosing 200% right away is a very interesting choice. I use all seachem products in my very, very heavily planted 55G and I'm still using the beginner doses, albeit at a more frequent interval than suggested. Potassium accumulates over time, and equilibrium adds 68ppm of K at 6dKH. I would honestly recommend using a potassium test kit if you're trying to fine tune the element

5: Using something like advance would probably have a better impact on growth than increases of that magnitude

6: I don't know much about that plant so I couldn't say for sure, but it does sound likely based on the growth pattern you observed
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post #3 of 6 (permalink) Old 09-19-2020, 05:07 AM Thread Starter
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Thanks @SirNut, sorry, your reply didn't flag up for some reason. Thanks for your input and suggestions!

Quote:
Originally Posted by SirNut View Post
4: It's hard to really say, but dosing 200% right away is a very interesting choice. I use all seachem products in my very, very heavily planted 55G and I'm still using the beginner doses, albeit at a more frequent interval than suggested. Potassium accumulates over time, and equilibrium adds 68ppm of K at 6dKH. I would honestly recommend using a potassium test kit if you're trying to fine tune the element
I didn't go to 200% right away. I actually started at 50% of suggested dose thinking that the recommended levels must be for highly planted tanks. After much reading I worked out the 'beginner' dose Seachem recommends is actually fairly low, so I gradually moved up to 100%, 150% and then 200%

But I finally did what I've thought I should really do for a while - plug all the numbers into the RotalaButterfly website, create a spreadsheet and work out my actual weekly dosing and fert balance. I now have a new schedule that I think is more balanced and tailored to my tanks.

For my planted tank (good light and CO2):
Flourish 100%
Potassium 0% (Equilibrium at water change adds more than enough)
Phosphorous 200%
Nitrogen 250% (fish load is quite low and nitrates always read zero)
Trace 100%
Iron 25%
- which gives 10:1:24 NPK ratio at about 50-60% of PPS dosing

For my shrimp tanks (no CO2):
Flourish 100%
Potassium 100% (use SS GH+ so not getting the big hit from Equilibrium in these tanks)
Phosphorous 200%
Nitrogen 250% (low fish load and nitrate always tests as zero)
Trace 100%
Iron most days 0%, once a week 30% of that days dose (want to keep low for shrimp)
- which gives a 10:1:15 NPK ratio at about 40-50% of PPS dosing

*Percentages are all of Seachem recommended 'beginner' dose and all are split across 6 days according to Seachem's recommended dosing schedule.

None of my plants are showing any signs of deficiencies that I can identify, algae isn't much of an issue in the established tanks and I've dropped water changes to every other week. I've not noticed any difference since switching to this new, tailored dosing plan. The point was to not be adding stuff I didn't need to (like extra dosing potassium when already using Equilibrium) and to balance between the different fert's. Also to minimise dosing in the shrimp tanks as far as possible without harming / overly limiting the plants. The plants look healthy, not growing too fast (which is a good thing for tank maintenance!), so far so good. Only one week in though so will see how it goes....


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post #4 of 6 (permalink) Old 09-19-2020, 05:41 AM
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It sounds like you're very happy with the way things are going. I'd leave it as is, maybe decrease your trace dosing gradually every week until you see some sort of deficiency. Then bump it up just a little to the amount before any deficiency showed up. Build up should be small once you get it dialed in.
The problem with dosing is that a lot of the fertilizers we put in our tanks are not stable. Some are only available for a short period of time and some interact with each other making them unavailable to plants.

Seachem rec. NPK doses are fairly low. I would only be careful with their traces. I have Flourish Trace but stopped using it regularly because I'm worried about the high zinc and copper content in the product. Maybe for the shrimp tank you can try cutting out Trace and stick to Comprehensive for your micro needs. In a non Co2 tank with low demanding plants, I don't think you need to dose Flourish Trace.
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post #5 of 6 (permalink) Old 09-19-2020, 03:07 PM Thread Starter
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Thanks @Betta Splendid,

I do keep wondering about the necessity of Seachem Trace for a low tech shrimp tank...
My problem is that I don't think I would be able to spot and/or correctly identify trace element deficiencies in my plants, hence the dosing at Seachem's recommended dose (and assumption that this standard dose if relatively low as per their macro fert's). I've spent a fair while reading threads on this forum and elsewhere (giving extra attention to insights provided by Mr Barr and the like) and the conclusion that I came to was that the levels of heavy metals (in particular copper and iron) in products like Seachem Trace are in the safe zone for shrimp. I have stopped dosing Seachem Iron as, whilst I think my original dose was still probably safe'ish, it didn't seem necessary. I hadn't considered zinc at all, but I assume that this will be similar as per the other metal traces.

I also concluded that Seachem Trace is basically almost pure water with the smallest amount of some exciting sounding elements dissolved. Someone far wiser than me in these matters pointed out that critters need these trace elements as much as plants, and that you would need to empty "half a bottle" into the tank to get anywhere near significant concentrations. This seems to make sense, I think...

You're probably right in saying Trace is not necessary for a low-tech, no Co2 shrimp tank with undemanding plants. But from the Seachem Trace bottle...
Copper 0.0032%
Zinc 0.0169%
...I'm not convinced that dosing Trace is that much different to topping up with pure RO! Adding up the %'s in the Guaranteed Analysis gives about 0.003%, or alternatively, that the bottle is 99.97% expensive water!

But maybe I'll back it off to 50% dose in the shrimp tanks anyway, as you suggest, and see if it makes any difference.
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post #6 of 6 (permalink) Old 09-20-2020, 03:50 AM
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Quote:
Originally Posted by en7jos View Post
Thanks @Betta Splendid,

I do keep wondering about the necessity of Seachem Trace for a low tech shrimp tank...
My problem is that I don't think I would be able to spot and/or correctly identify trace element deficiencies in my plants, hence the dosing at Seachem's recommended dose (and assumption that this standard dose if relatively low as per their macro fert's). I've spent a fair while reading threads on this forum and elsewhere (giving extra attention to insights provided by Mr Barr and the like) and the conclusion that I came to was that the levels of heavy metals (in particular copper and iron) in products like Seachem Trace are in the safe zone for shrimp. I have stopped dosing Seachem Iron as, whilst I think my original dose was still probably safe'ish, it didn't seem necessary. I hadn't considered zinc at all, but I assume that this will be similar as per the other metal traces.

I also concluded that Seachem Trace is basically almost pure water with the smallest amount of some exciting sounding elements dissolved. Someone far wiser than me in these matters pointed out that critters need these trace elements as much as plants, and that you would need to empty "half a bottle" into the tank to get anywhere near significant concentrations. This seems to make sense, I think...

You're probably right in saying Trace is not necessary for a low-tech, no Co2 shrimp tank with undemanding plants. But from the Seachem Trace bottle...
Copper 0.0032%
Zinc 0.0169%
...I'm not convinced that dosing Trace is that much different to topping up with pure RO! Adding up the %'s in the Guaranteed Analysis gives about 0.003%, or alternatively, that the bottle is 99.97% expensive water!

But maybe I'll back it off to 50% dose in the shrimp tanks anyway, as you suggest, and see if it makes any difference.
My apologies. It's actually Zinc. I had Copper confused with Flourish Comp vs Tropica. But it's Zinc that is much higher in Flourish Trace compared to other ferts. Flourish Comp for Zinc is 0.0007%, Tropica is 0.002%, so Zinc content in Trace is over 24x higher than Flourish Comp and about 8.5x higher than Tropica. The dosage in ml is a lot higher with Trace as well.
But you're right, it should still be on the safe side because Seachem says all their ferts are shrimp safe. I stopped dosing Trace because I only do 10-20% water changes a week on my tank and was worried about Zinc build up, especially after reading about trace toxicity this past year.

I'm glad you brought up the critters need for trace elements. I hadn't considered this and always assumed they get it from their food. Maybe I should try dosing Flourish Trace again. Oh the confusion hahaha here I am telling you on my previous post to stop Trace and now I'm thinking about dosing Trace again. I have to say, those trace toxicity threads have been messing with my head for a while now lol.
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