# EDTA? DTPA? Which one should I use?



## Dantra

Folks, like me, with zero/low KH and very acidic water will find that it has an effect on their needs for Fe input and quality of chelate. So my question is, what, if any is the "rule of thumb" pertaining to Fe in reference to soft water and hard water?

Is EDTA better used for soft water?
Is DTPA better used in hard water?

I am looking to place an order so I appreciate any input in ordering the one better suited for my tank.

Thanks
Dan


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## wet

Hey, Dantra.

DTPA is the better (stronger) chelator. While we need strong chelators in hard water, strong chelators are still stonger than weak chelators in soft water. In your very soft water, EDTA may be fine. But if you want your Iron to stay it its ferrous (immediately usable) state for as long as possible (and you do!), get DTPA instead of EDTA, regardless of whether your water is soft or hard. And if you have the dough, maybe even consider an even better chelator (HEEDTA) and let us know how it goes 

(Is anyone else intrested in HEEDTA and splitting an order? I am becoming more interested but definitely won't need 5lbs...)


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## nfrank

Wet, i could be interested in getting some.

We know that it is more stable in hard water. In fact, for stability, EDDHA >HEEDTA > DTPA> EDTA. Is there any evidence that HEEDTA is also less photosensitive than DTPA and EDTA ?

Regarding the advantages of hard water stability, i assume that this really pertains to keeping it in solution in a concentrated fert mixture, not necessarily for the aquarium. WDYT?

While poking around on the net, i just found this Polish Product

BTW, for other recent APC discussion of the same (old) topic see Which Chelator?


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## Dantra

Thanks guys, I recently added macrandra to my tank and realized that I needed to supplement more iron. The results speak for themselves however I needed to add more iron than I originally thought. That's why I asked about the difference in chelators. 

Wet, i would be interested in getting some HEEDTA as well, just to give it a go and see how it preforms to what I've been using.

Perhaps if we get enough people interested, it will help keep the cost down.

Dan


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## wet

Neil,


> Is there any evidence that HEEDTA is also less photosensitive than DTPA and EDTA ?


I am sneaking in posts at work and have not hunted google links yet, but I _think_ your experience with once a week dosing with DTPA in your soft water tank suggests that the photosensitivity of DTPA isn't super critical and I wonder if you could get away with even less frequent Fe dosing if you did not do water changes. (Ignoring the other benefits of water changes, of course.) When I get around to googling I hope that the evidence says EDDHA is even more lenient of light. But I suspect (still a guess) these chelators are only relevant in solution or soil and not degrees of light.


> Regarding the advantages of hard water stability, i assume that this really pertains to keeping it in solution in a concentrated fert mixture, not necessarily for the aquarium. WDYT?


Disregarding light, I would think it pertains no matter where the water is -- dosing container or aquarium -- no? Makes sense the tiny critters in our garden's water column would affect it vs DI water brought to the same pH/KH in a container. Again your and Claus's experience with once a week dosing makes me guess this is mostly ignorable and makes me miss the advantages of keeping a soft water tank 

That trace product is appealing -- man, it sure is hard to find quality chelates in traces without adding NPK!

Neil and Dan,
Let's explore my using the hobby portion of my refund to front the cost of this. In the time I had with google and after your posts, I am leaning towards EDDHA for our potential experiment because, hey, why mess around. The cheapest price I found for dry is this ($105.34 shipped ground): http://www.bes-tex.com/products.php?kei=8 Linkage to others?

If I did front it I'd probably add a bit for hobby dough (or trade straight up for plants I want) to each portion at 1/2lb - 1lb quantities and put up an online calculator for it. I'll link this to a FS Forum interest check if it works out. This stuff is 6% Fe vs the 10% Fe Rex/GLA/etc sells but 0.5lb should still last roughly forever. Still down?


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## Tex Gal

I have moved Wet's selling offer to the For Sale column. If you are interested you need to look there.


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