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Magnesium Sulphate... do you dose it?

Arana

Arana

Member
Joined
12 Oct 2007
Messages
1,296
Location
London
I have been dosing EI using the excellent NutriCalc recommended by Matt (thanks Matt 😀 ) without any issues except for some minor hair algae on my vallis but i have noticed that in a lot of EI articles i have read lately there is no mention of Magnesium Sulphate in the dosing regime, why are we dosing this? is this just for the Mg? i'm not likely to change what i'm dosing because it's working so well. I just want to be sure i understand why i'm doing it. :?

Incidently, if you need to clean Hair Algae off of your plants find some goldfish! i tranfered mine to my 8 year old sons 120 goldfish setup and they cleaned a huge bunch of it in about an hour! they seem to love the stuff! 😀
 
To be honest, I wasn`t aware of MgSO4 being part of the EI regime.

Extra Mg can be added via GH booster at water change time. This will also supplement Ca levels as well. I have very soft tap water, so I use GH booster to compensate for this.

The Goldfish bit is interesting. My eldest daughter keeps a pair, so I1ll bear them in mind.

Dave.
 
Magnesium is added in the form of magnesium sulphate if your water has low magnesium levels. GH is made up of calcium and magnesium and generally speaking your tap water has plenty of both. Sometimes though, as for me, tap water is nearly all calcium so you have to add extra magnesium. If your dosing is working fine then there is probably no nead to add any Mg. With low GH it's best to add some GH booster as this adds both Calcium and Magnesium in the correct ratio. Low magnesium syptoms are yellowing leaves with the veins staying green and the leaf edges of fast growing stem plants curling. I get both of these happening in my high light tank if I don't add Mg.

James
 
thanks guys, i'm glad i asked the question now! there's no problem with the GH in my tap water and no apparant problems with deficiancies in my plants, so now i'm not sure what to do :? maybe i'll remove the magnesium sulphate from the dosing regime and let the plants tell me if they like it or not.

i started adding it simply because nutricalc give me an amount to dose 🙄

could the magnesium sulphate have been a contributating factor with the hair algae problem?
 
Arana said:
Matt - maybe one of us should stop and the other should continue so we can compare the differances 8)
Click to expand...

Ill stop, I have some good records of my tanks performance in the last month since my NO3 mess-up. I also have good photos and a good handle on all my plants, I should be able to spot any differences pretty easy.
 
Frolicsome_Flora said:
Ill stop, I have some good records of my tanks performance in the last month since my NO3 mess-up. I also have good photos and a good handle on all my plants, I should be able to spot any differences pretty easy.
Click to expand...

Great! 😀 Thank you very much 😀

Does anyone else out there dose it?
 
Hi,
The MgSO4 was introduced as an adjunct to EI back when it was fashionable to only use soft water for plants. A lot of people started using RO water so they wound up having to dose Calcium and Magnesium back into the water. 🙄
You can get a water quality report on the web for your area but one problem is that they only publish the GH value in terms of "equivalent CaCO3" so it's never clear how much Mg is available. If your tap's GH is up past 7 degrees or so, more than likely there is sufficient Mg. I would only dose the MgSo4 in high light applications using RO water or if the tap water was soft, and even so, as Dave and JamesC pointed out, a much better option would be to dose a pinch of GH booster once a week at water change - and that makes life easy. 8)

Some places in the world don't have access to GH booster though, so that might be one reason why NutriCalc still has it in there.

If you live in London and your water supplier is Thames Water Company you definitely don't need to add MgSO4 :shock:

Cheers,
 
ceg4048 said:
Hi,
If you live in London and your water supplier is Thames Water Company you definitely don't need to add MgSO4 :shock:
Click to expand...
That's what I would have thought as well. Thames water don't really say much in their report about GH except to say what the value is in terms of CaCO3. I used to get problems with leaf curling and yellow leafs so added MgSO4 which seemed to help loads. I even went out and brought GH and Ca test kits to measure. I know test kits aren't great but they give you an idea. Knowing the GH and Ca you can work out the Mg. I even doubled up the quantities to get a bit more accuracy, but even so the results came out the same which is practically no Magnesium. I might contact Thames Water and see if I can get some more info out of them.

On a side note the water round here is very odd. When I first moved here about 10 years ago our kettle used to fur up really quickly and need constant descaling. Then all of a sudden about 8 years ago it suddenly changed and I've not had to descale the kettle once since then. Even when I got rid of an old washing machine the element was still shiny with no scale. Very odd as the water is very very hard here. And before anyone asks, no I don't have any water softeners. Perhaps Thames Water are adding something to the water??

If anyone could shed some light on this it'd be most appreciated.

James
 
OK, thought I'd do some testing of my tap water supplied by Thames Water to see what the results are at the moment. I was quite amazed and the figures I get aren't fiddled in any way. I used the Hagen GH/KH and Ca test kits.

GH
15 drops. Multiply by 20 to get mg/l = 300 multiply by 0.056 = 16.8 dH. Thames water quote an average of 315mg/l for my area so this ties in fairly well.

KH
20 drops. Multiply by 10 to get mg/l = 200 multiply by 0.056 = 11.2dH

Ca
6 drops. Multiply by 10 to get mg/l Ca = 120. Convert to CaCO3 multiply by 2.5 = 300


So GH mg/l - CaCO3 mg/l = MgCO3 mg/l which in my case is 300 - 300 = 0 mg/l of MgCO3.

I have done these test over 2 plus years now using different test kits and always come up with nearly the same answer. Sometimes it comes out with a tiny bit of magnesium and sometimes with a tiny bit more calcium than GH but I put this down to experimental error. Amazingly with a GH of about 17 I have zero magnesium. Plants will back me up on this as they do much better with magnesium added.

The GH does vary a bit around here as well. A year ago it got up to the mid twenties, but still no Mg.

Anybody else with Thames Water and want to do some tests? Be interesting to see the results.

James
 
Wow James GH of 17 and no Mg? Incredible! OK, I'll have to recant my earlier statement - it looks like you can have high GH without Mg being present. Everything must be made of limestone out by your way. :shock:

Cheers,
 
JamesC said:
Ca
6 drops. Multiply by 10 to get mg/l Ca = 120. Convert to CaCO3 multiply by 2.5 = 300


So GH mg/l - CaCO3 mg/l = MgCO3 mg/l which in my case is 300 - 300 = 0 mg/l of MgCO3.
Click to expand...

Isn't the assumption here that the Ca test is measuring CaCO3? Couldn't there also be CaSO4? CaCl? Or are these not soluble?
 
Knew I had a photo somewhere. This is my Rotala Macrandra showing serious deficiency problems. No magnesium is added initially. About 2/3 rds of the way along 10ppm Mg is added in the form of magnesium sulphate. Quite a change. No other parameters are changed.

Magnesiumstunting.jpg

James
 
If you look at nearly all plant deficiency guides they state that magnesium affects old leaves which just goes to show there is a lot more to plant deficiencies than first meets the eye. This kind of stunting can actually be caused by several factors so it took me a little while to work out what was causing it. I just didn't believe at the time that with a very high GH I had no magnesium.

James
 
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