# Which fertilizers you use on hard water with good results?



## kadoxu (9 Nov 2016)

Hi everyone,

The title says it all. I would like to know what fertilizers you have been using, with good results, specially in hard water.

My water can go up to 25 dGH at some times and I've been having some trouble finding a good alternative regarding ferts.

I'm thinking about getting an RO unit, or start collecting rain water, but want to know if someone was able to do it without changing water hardness.


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## roadmaster (10 Nov 2016)

Fe from DTPA would be my choice for hard water.
Not sure if hard water would matter much with regard's to NPK
What little Mg is possibly in trace mix such as CSM+B might not last long enough to affect GH further before plant's used it up.
Hard water is what it is with regards to Calcium/magnesium but many have fairly hard water .
My source water is 12 dgh and I have seen improvement with DTPA in addition to EDTA found in trace mix CSM+B


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## ian_m (10 Nov 2016)

My water is over 320ppm (22 Clarke) I use cooled boiled water to make my EI ferts and are not having any plant issues. Some people report precipitates in their EI solutions when mixing using very hard tap water, so in that case use cooled boiled water.

You are best to really use tap water if you can. Remember RO water can work out about 2-3p per litre, if on a water meter.

I pay £3.20 per 1000litres -> 0.32p per litre. Typical RO using maybe wastes 5 litres of water for each litre of RO, so that is 2p per litre (x6). Most RO units, unless pumped and using warmed water will be worse than this maybe even 10:1, so 3.2p per litre.


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## markk (10 Nov 2016)

kadoxu said:


> Hi everyone,
> 
> The title says it all. I would like to know what fertilizers you have been using, with good results, specially in hard water.
> 
> ...


Hi kadoxu,

As you know, I'm just up the road from you and have been using EI mixed in either RO or boiled tap water for a number of years - without any obvious/major issues.

As ian_m has suggested, you might want to think twice about an RO unit. I'm not on a meter but still found the hassle of storage etc with an RO unit to be a pain. These days I have a couple of the 25litre plastic jerry cans that I fill every so often from the LFS. I use this to mix ferts, top off tanks, clean glass etc - and occasionally mix in more when doing a water change to just keep the TDS down a little.

Cheers, Mark


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## dw1305 (10 Nov 2016)

Hi all,





roadmaster said:


> Fe from DTPA would be my choice for hard water.


Iron solubility is definitely an issue, and DTPA is a better chelator than EDTA at higher pH values. 





roadmaster said:


> Not sure if hard water would matter much with regard's to NPK


No, it doesn't for nitrogen (N) and potassium (K), mainly because nearly all nitrogen and potassium compounds are soluble.  Phosphorus (P) will form insoluble <"calcium phosphate complexes"> compounds at high pH. (from <"The nature of phosphorus in soils">).







These are the availability curves against pH for nutrient in soils.



 

You may also get problems with the calcium (Ca):magnesium(Mg) ratio in very hard water <"in the UK">, although this can be compensated for by adding more magnesium.





kadoxu said:


> or start collecting rain water,


I've always used rain-water in my tanks, but I've been fortunate enough to live somewhere where it has been possible to collect and store a large volume of water. It is very much <"my preferred option">.

If I couldn't use rain-water I'd use tap, like "ian_m" and "markk" suggest, mainly because an RO unit will need to discard even more water with a hard "saltier" water supply.

It might limit what you can grow and keep, but I think there are plenty of plants and fish that thrive in hard water.

cheers Darrel


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## kadoxu (10 Nov 2016)

Thanks guys!



ian_m said:


> You are best to really use tap water if you can. Remember RO water can work out about 2-3p per litre, if on a water meter.
> 
> I pay £3.20 per 1000litres -> 0.32p per litre. Typical RO using maybe wastes 5 litres of water for each litre of RO, so that is 2p per litre (x6). Most RO units, unless pumped and using warmed water will be worse than this maybe even 10:1, so 3.2p per litre.





markk said:


> As ian_m has suggested, you might want to think twice about an RO unit. I'm not on a meter but still found the hassle of storage etc with an RO unit to be a pain.





dw1305 said:


> I've always used rain-water in my tanks, but I've been fortunate enough to live somewhere where it has been possible to collect and store a large volume of water. It is very much <"my preferred option">.
> 
> If I couldn't use rain-water I'd use tap, like "ian_m" and "markk" suggest, mainly because an RO unit will need to discard even more water with a hard "saltier" water supply.



RO is definitely a last resort option. I'm leaning towards rain water, since I'm moving to a new place with a big garden.



roadmaster said:


> Fe from DTPA would be my choice for hard water.





roadmaster said:


> My source water is 12 dgh and I have seen improvement with DTPA in addition to EDTA found in trace mix CSM+B





ian_m said:


> My water is over 320ppm (22 Clarke) I use cooled boiled water to make my EI ferts and are not having any plant issues. Some people report precipitates in their EI solutions when mixing using very hard tap water, so in that case use cooled boiled water.


I did try to change from Seachem Flourish to APF's EDTA trace elements, but I'm not having good results with it. I think one of my main mistakes was mixing the ferts directly in untreated/not boiled tap water. I'll have to get some DTPA Iron to try it out.



dw1305 said:


> You may also get problems with the calcium (Ca):magnesium(Mg) ratio in very hard water <"in the UK">, although this can be compensated for by adding more magnesium.


I do add Mg to my Macro solution.



dw1305 said:


> No, it doesn't for nitrogen (N) and potassium (K), mainly because nearly all nitrogen and potassium compounds are soluble. Phosphorus (P) will form insoluble <"calcium phosphate complexes"> compounds at high pH. (from <"The nature of phosphorus in soils">).


The other problem I think I have is with the soil. I think it's the reason why my PH is so high. But since I have no other place to leave the critters, the soil change will have to wait.


I'm thinking about adding some peat to my external filter to bring PH down. Does peat also reduce water hardness? Or is it just a result of a more acidic environment? Or am I just crazy now?! 

Does anyone know where I can get DTPA chelated Iron?


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