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Discussion Starter · #1 ·
I think I'm finally getting wrapped around all of this, but I have a couple more questions. I'm going to be dosing a 75 gallon tank with 60-65 gallons of water. The EI page reads:

60~80gal
50% H20 change-weekly
3/4 Tsp-KN03 3x a week
3/16 Tsp-KH2P04 3x a week
1 Tsp-GH booster once a week
15ml 3/16Tsp-Trace 3x a week
Optional
4-8ml-Fe/Iron 3x a week

On the Barr Report page the iron is not listed. My local water is very hard, so I suspect I'll be ok without the GH booster. Iron per the water board is ~.19 ppm.
I have two questions:
1) The places that I've looked at for dry ferts (Rex Grigg and aquariumfertilizer.com) both list K2SO4 in their combo packs, although I don't see it in the EI list. Is this for the potassium or the sulfur? Either way, how likely am I to need that? I don't see it mentioned much in the EI threads.
2) Is the iron needed, or am I likely to have enough of that from the CSM+B? It seems odd that it isn't mentioned much in the EI threads here and over at the barrreport.
 

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Time marches on, and new information and ideas surface. When EI was started most people didn't try to dose more iron, so the list of dosages didn't include any, beyond that in CSM+B. Now, more people are finding that extra iron can be very helpful, so the latest dosage tables list iron. K2SO4 is useful if your tap water is high in nitrates. You can reduce the KNO3 dosing and make up the difference with K2SO4 for more potassium.

If you look at EI as more of a way of thinking about fertilizer dosing - always have more than enough of every nutrient available to the plants, and rely on big water changes if needed to avoid building up any dangerous level of any of the nutrients - you can be pretty flexible with it. Dose every day, dose twice a week, dose weekly, dose extra potassium, dose extra phosphate, etc. Do bigger water changes less often, do smaller water changes more often. Do few water changes at all. The table is a great starting point.
 

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Discussion Starter · #3 ·
Thank you as always Hoppy. I may have limestone pouring out of my tap water, but only ~2.5ppm nitrate. Given that I would like to eventually go to automated dosing of my ferts (I'm out of town regularly), is there any particular form of iron that I should use or avoid? I've read that the EDTA chelates aren't stable above a pH of 6, although other places seem to point that towards light sensitivity. I don't mind dosing it daily, but want to be able to mix it up in at least 2 week batches.
I read this: http://www.aquaticplantcentral.com/forumapc/fertilizing/67958-chelated-iron-yes-no.html
but didn't reach any hard conclusions.
 

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I'd use a mix of 75% CMS+B and 24% DTPA Fe
Some folk prefer a stout solution, other think Fe is toxic and must be dribbled in very slowly at mini amounts.

I prefer a richer amount, never had any issues.

With the limestone tap, the DTPA will be better for you.
I target about 0.5-0.7ppm per dose 3x a week, but it might wander off higher.
 

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Discussion Starter · #5 ·
Thank you Tom. A couple more questions stemming from that:
1) What is the assumed concentration of the DTPA? I've found places claiming between 5 and 13% FE, although the difference may be the chelating agent, I'm not entirely sure.
2) How long will the DTPA be useable once in a solution? It will be in the dark at room temperature (55-75*F). I'd prefer to make it in 2 week batches, but if it decomposes after 24 hours obviously I won't be doing that.
3) It looks like GLA sells the DTPA Fe at 11%. Unfortunately the aquariumfertilizer.com stuff is ferrous gluconate and EDTA (13%). I've written Rex to ask what his is. Is there anywhere else I should check?
4)What can't I mix? I'm under the impression that there is some interaction such that the KNO3, KH2PO4, DTPA Fe, and traces (lets assume CSM+B) can't all be kept in solution together, but I'm not clear if it is the P, Fe, or traces that cause problems. Which combination causes issues?
 

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The only things you can't mix in a fertilizer solution is KH2PO4 and iron. Those will chemically combine, making an insoluble compound out of the iron, so it just settles in the fertilizer bottle unavailable to be dosed.
 

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Thank you Tom. A couple more questions stemming from that:
1) What is the assumed concentration of the DTPA? I've found places claiming between 5 and 13% FE, although the difference may be the chelating agent, I'm not entirely sure.
2) How long will the DTPA be useable once in a solution? It will be in the dark at room temperature (55-75*F). I'd prefer to make it in 2 week batches, but if it decomposes after 24 hours obviously I won't be doing that.
3) It looks like GLA sells the DTPA Fe at 11%. Unfortunately the aquariumfertilizer.com stuff is ferrous gluconate and EDTA (13%). I've written Rex to ask what his is. Is there anywhere else I should check?
4)What can't I mix? I'm under the impression that there is some interaction such that the KNO3, KH2PO4, DTPA Fe, and traces (lets assume CSM+B) can't all be kept in solution together, but I'm not clear if it is the P, Fe, or traces that cause problems. Which combination causes issues?
YOu won't get a response from rex. Don't send him you're money, as you'll just have to spend a month disputing it to get it back. Seems as though he has gone MIA and no longer checks in, his site is still up though so it seems many people make this mistake...

Storing your solutions in dark, and using a preservative(ie Flourish excel(glut) or HCL) are the key to making them last.... This is something I have a little experience with....................... :icon_smil
 

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Discussion Starter · #8 ·
Well I guess it's GLA then. I'd like to get all of this stuff at one place, and they seem to be the only folks that have everything, unless I'm missing something obvious (please point it out if so). Thanks all for the help.
 

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Is there any point in me adding K2SO4 given that I'll already be using the KNO3 and KH2PO4 (low nitrates in my tap water)?
I sometimes fold this into the GH booster which is 2:1:1 K2SO4: CaSO4: MgSO4

With IN limy water.....you might add just the K2SO4 and MgSO4(Epsom salt), these can both better added to the Trace mix also at about 3-4: K+/Mg to CMS/DTPA.

DTPA will last roughly 1-2 days in solution in harder tap.
ETDA/Gluc, maybe a few minutes, hours.

Without actually labeling 59Fe and then measuring the uptake in plants, it's hard to say. Since no one has ever done this for aquatic plants, these are mere guesses.

The only dosing of Fe was done by Haller with Hydrilla, I think optimal growth occured at 6 ppm, and max uptake at 8ppm. About 10X what I dose, and about 60-80X more than some bozo's claim is optimal.
 

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Also, do yourself a favor, if mixing stock solutions. Use Distilled or RO water. Distilled is better. Then add HCL or Excel to preserve and lower pH further.

Boiling the solution with help it mix. WIth micros it is like magic. All of the sudden it goes from cloudy to clear brown. YOu should see what it looks like in a vat of 100 gallons of it....
 

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Discussion Starter · #13 ·
Ok, so add the K2SO4 to prevent potential potassium shortage, and the epsom salt with water changes to prevent low magnesium. Both will be added to my trace bucket (so CSM+B, iron, K,Mg). How long will the DTPA last if I make it in distilled rather than tap water (in a dark bottle under the tank)?
Overstocked, what are you defining as a stock concentration, and how much HCl or Excel are you adding as a preservative?
 
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