# Can I replace Cal-Mag with Dolomite Lime?



## Delta223 (Apr 29, 2010)

I've heard dolomite lime is the same as Cal-Mag which I currently use. Does that mean I can simply use the garden lime in my hydro garden instead of the cal-mag?

Thanks


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## doc111 (Apr 29, 2010)

Delta223 said:


> I've heard dolomite lime is the same as Cal-Mag which I currently use. Does that mean I can simply use the garden lime in my hydro garden instead of the cal-mag?
> 
> Thanks


Maybe. It's going to depend on what kind of nutes, water, and soil you are using. Dolomite lime is a good source of calcium and magnesium but it's kind of slow acting. Get the finest stuff you can, prilled is the best. It also raises your pH so you don't want to get too crazy with it. You also want to mix it in* thoroughly*! I can't stress this enough. Top dressing or watering it in ain't gonna cut it. Cal-mag has iron as well. Dolomite lime doesn't. Happy growing my friend.


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## Wetdog (Apr 29, 2010)

In hydro?

Not so sure about that. It is basically ground up limestone and not really soluble. Not hydro soluble anyway.

Wet


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## doc111 (Apr 29, 2010)

Wetdog said:


> In hydro?
> 
> Not so sure about that. It is basically ground up limestone and not really soluble. Not hydro soluble anyway.
> 
> Wet


Whoops! I missed that part. Ummm, I'm gonna say no, you won't be able to replace your cal-mag if you're doing hydro. Sorry buddy.


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## fatman7574 (Apr 29, 2010)

Cal-mag is a cheap mix of calcium nitrate, magnesium nitrate and chelated iron sold at a high price. It is much simplier to just add calcium nitrate, magnesium sulfate and chelated iron. They are all readily available even on eBay. 

Dolomite lime is powdered magnesium carbonate. It is a solid, and as far as hydroponics it is not considered soluble at all.

Magnesium nitrate is a odd ball fertilizer seldom used, but China sells it cheap. Cheaper than magnesium sulfate. There is no need for more nitrate beyond what the calcium nitrate supplies. And the magnesium level of magnesium sulfate is 10% with the magnesium nitrate providing 9.5% magnesium. At $18 per quart it is a rip off, but it is easy to use and easy to find. It is very dilute and cost about $1 per gallon or less to produce.


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## Delta223 (Apr 29, 2010)

How would I create a solution that's not too concentrated and also in the right ratio of nutrients?


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## fatman7574 (Apr 30, 2010)

Delta223 said:


> How would I create a solution that's not too concentrated and also in the right ratio of nutrients?


*fatmans Cal-Mag*

*ppm*
Nitrogen 200
Magnesium 120
Calcium 259
Sulfur 160
Iron 10.00


*Grams (ounces)*
Calcium Nitrate 488.9 
(17.25)
Magnesium Sulfate 464.0 (16.37)
Iron Chelate 38.57 (1.36)

*Volume of Stock Solutions 1 gallon
Dilution Rate 100 to 1*

*Calcium nitrate 32 ounces $12 http://cgi.ebay.com/Calcium-Nitrate-15-5-N-prilled-2-lb-bags-/110524898266?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item19bbcc1bda*

*Magnesium Sulfate 32 ounces $2.80 http://cgi.ebay.com/2-LBS-EPSOM-SALT-MAGNESIUM-SULFATE-USP-/200460832797?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item2eac65901d*

*Chelated Iron 50 grams $4.49 (ie $226 for 5 pounds) http://cgi.ebay.com/Chelated-IRON-13-Fe-EDTA-Aquarium-Fertilizer-/170476421809?cmd=ViewItem&pt=UK_Pet_Supplies_Fish&hash=item27b12fc2b1*

*The above prices are eBay prices.*

*Crop king (green house online supplier) Obviously large quantities are a lot cheaper per unit volume. the below prices are about the vaerage cost across the country at large green houses. Magnesium sufate is commonly known as Epsom Salts and can be bought in neraly allrocery stores in the vitamin and medical supply section. Chelated iron is sold for lawns in about every large lawn and garden center to include Home Depot, Lowes, Fred Meyers and Walmart. Calcium nitrate is pretty common at large lawn and garden supply centers. The money you would save buying from an online store rather than a local farm and garden store you would likely just pay in shipping costs.

*Magnesium sulfate 16 ounces $1.71 http://www.cropking.com/HydroponicSupplies/index.php?main_page=index&cPath=264_268&zenid=0e9feea96fbd8e27fdd3725619fdc9e7

Magnesium Sulfate 50 lbs $35.68 http://www.cropking.com/HydroponicSupplies/index.php?main_page=index&cPath=264_268&zenid=0e9feea96fbd8e27fdd3725619fdc9e7

Calcium Nitrate 50 lbs $29.95 http://www.cropking.com/HydroponicSupplies/index.php?main_page=product_info&cPath=264_267&products_id=1105&zenid=0e9feea96fbd8e27fdd3725619fdc9e7

Chelated Iron 5 lbs $49.31 http://www.cropking.com/HydroponicSupplies/index.php?main_page=index&cPath=264_269&zenid=0e9feea96fbd8e27fdd3725619fdc9e7


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## doc111 (Apr 30, 2010)

Delta223 said:


> How would I create a solution that's not too concentrated and also in the right ratio of nutrients?


Yeah you could mix your own but seriously man, who has the time or resources to mess around with it? Cal-mag may be overpriced but there are a few brands of it which are a few bucks cheaper than botanicare's version. Happy growing my friend.


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## Delta223 (Apr 30, 2010)

which brands do you suggest doc? Outside of AN and BT my knowledge is absent.


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## fatman7574 (Apr 30, 2010)

doc111 said:


> Yeah you could mix your own but seriously man, who has the time or resources to mess around with it? Cal-mag may be overpriced but there are a few brands of it which are a few bucks cheaper than botanicare's version. Happy growing my friend.


doc11 If i wrote water was wet, you would argue that ice is not wet. This is just another reminder of why you still remain on my ignore list. With your attitude I suspect you are also a buyer of Fat Mikie's over priced convenience products. Mixing nutrients is very simple. No harder than measuring the pH and EC of your nutrients and adjusting them. The thing is mixing your own nutrients only has to be done a few times per year instead of every day. Plus you get exactly what you want or need, not what your stuck with buying that is mixed for the average needs of the masses. 

Get the ingredients you need to mix cal-mag and you are close to having all you need to mix full two part formulations. I consider mixing my own fertilizers a relaxing experience, not a chore or inconvenient task. the time required is minimal and the resources, a few buckets, a large plastic spoon and a scale.


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## SupraSPL (Jun 1, 2010)

I have been wondering the same thing about dolomite lime. I did an experiment by crushing up dolomite lime and adding it to R/O water. The R/O started off at a pH of 6.0 and began to rise. After several hours it stabilized at 7.0 (I was using aquarium drops to measure)

Unfortunately I don't have an EC meter but there did seem to be less lime crystals in the bottom of the container. Could any of the calmag dissolve and be available to plants if watered in? It really would be convenient if we could use dolomite instead of calmag plus to fix up R/O water. Why do we need nitrogen, sulphur and iron wouldn't that come from the ferts?


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## doc111 (Jun 1, 2010)

SupraSPL said:


> I have been wondering the same thing about dolomite lime. I did an experiment by crushing up dolomite lime and adding it to R/O water. The R/O started off at a pH of 6.0 and began to rise. After several hours it stabilized at 7.0 (I was using aquarium drops to measure)
> 
> Unfortunately I don't have an EC meter but there did seem to be less lime crystals in the bottom of the container. Could any of the calmag dissolve and be available to plants if watered in? It really would be convenient if we could use dolomite instead of calmag plus to fix up R/O water. Why do we need nitrogen, sulphur and iron wouldn't that come from the ferts?


Dolomite lime is fairly slow acting. Too much of it in your medium will lockout other nutrients so it's not a good idea to add cal-mag in this way. It needs to be mixed in the soil prior to planting in order to be effective. Even then it may be too slow acting for cannabis and you may still have to add some sort of cal-mag supplement. For hydro, it's utterly useless.


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## NLXSK1 (Jun 2, 2010)

patlpp said:


> So is your fuckin brain


Hey Pat? Could you try to add something constructive to the conversation?

So far all I have seen you manage to do is insult people and get interesting threads locked...


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## patlpp (Jun 2, 2010)

NLXSK1 said:


> Hey Pat? Could you try to add something constructive to the conversation?
> 
> So far all I have seen you manage to do is insult people and get interesting threads locked...


Blow me........


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## doc111 (Jun 2, 2010)

NLXSK1 said:


> Hey Pat? Could you try to add something constructive to the conversation?
> 
> So far all I have seen you manage to do is insult people and get interesting threads locked...


Stalkers and trolls seldom have anything constructive to add.


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## NLXSK1 (Jun 2, 2010)

patlpp said:


> Blow me........


I think you hurt my feelings... *checks feelings*

Yep, they are bleeding...


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## SupraSPL (Sep 23, 2010)

Finally got a ppm meter. I mixed 800ml of R/O water with 200ml thoroughly rinsed pelletized dolomite lime (to get rid of the brown clay or whatever it is on the outside). The R/O started off at 4ppm and rose to 16 ppm when I added the (imperfectly) rinsed lime. So far it has been 2.5 hours and the ppm has risen to 28ppm and the ph is at 6.8. Hopefully it is calcium and magnesium that is available to the plant and I expect the ppm to continue to rise. If so may be the answer to the op's question.


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## LarryOG (Dec 3, 2013)

Sorry to resurrect this thread but it makes me laugh when i read it. Calcium nitrate and magnesium sulfate precipitate when mixed unless chelated. Don't waste your time trying to make your own cal-mag with the mix listed.


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## churchhaze (Dec 5, 2013)

This is true if you mix them concentrated, but you can add the magnesium sulfate and calcium nitrate directly to your reservoir with no problems.

Who needs to replicate cal-mag anyway. Just use calcium nitrate and magnesium sulfate as separate ingredients. As fatman said a few years ago, if you have calcium nitrate and magnesium sulfate, you already have almost half of the salts you'd need to make a complete hydroponic mix.

Two birds with one stone. They become supplements AND main ingredients at the same time.

Cal-mag is a waste of money.

http://www.cropking.com/HydroponicSupplies/index.php?main_page=product_info&cPath=264_265&products_id=342

7 bucks for 5lb.

Just go grab a big bag of calcium nitrate and you're set for life.



LarryOG said:


> Sorry to resurrect this thread but it makes me laugh when i read it. Calcium nitrate and magnesium sulfate precipitate when mixed unless chelated. Don't waste your time trying to make your own cal-mag with the mix listed.


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## twistedwords (Dec 5, 2013)

ah....just get some epsom salt and dilute it down and foliar spray it. No need for calcium as there is plenty in your nutes and water. The only reason they put calcium in with magnesium is so the magnesium can bind with the calcium in your mix.


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## churchhaze (Dec 5, 2013)

If the problem is not enough magnesium, then yeah just using epsom salts makes a lot more sense than using a combination of calcium nitrate and magnesium nitrate.

This is exactly why it makes sense to get separate ingredients. The only reason they put them together is because of marketing. People love their "cal-mag".

Calcium nitrate is arguably the main ingredient to all hydroponic recipes, yet the majority of people think it would be a waste to have some laying around.



twistedwords said:


> ah....just get some epsom salt and dilute it down and foliar spray it. No need for calcium as there is plenty in your nutes and water. The only reason they put calcium in with magnesium is so the magnesium can bind with the calcium in your mix.


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