# [Wet Thumb Forum]-GH Calcium and Magnesium question



## imported_Austin (Nov 8, 2004)

Good day all

I seem to be having a problem with the hardness of my water from my tests and what I have found out what would be the best approach.

The GH in my tank is approx 80-90 ppm and from my water company im told my TDS is around 180.

Currently I am using Kents R/O to try and raise my GH and also add baking soda to saise my KH(70ppm), running pressurized CO2 with my PH at 6.8 to 6.6

My other parameters before I ask the question are as follow


Using estimated index dosing (46gal tank)
NO3 10-15ppm
K 20ppm (3/4tsp every second day)
P 1.5ppm
Fe 1ppm

Now onto the 2 questions first Does RO right affect my CO2 calculations?

Secondly my main concern is some of my plants specifically ludwiga cuba are showing sign of deficiency specficly leaves curling/browning. Which leads me to beleive cal/mg deficiency.

What other alternatives do I have for raising my Ca and Mg along with hardness would calcium carbonate and magnesium sulfate(i think thats what its called) do both gk and Kh also solving my nutrient deficiency.


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## Roger Miller (Jun 19, 2004)

An actual deficiency of calcium would be a little surprising. A magnesium shortage may be a little more likely. In extreme cases it is possible for apparent deficiencies to be caused by large ion imbalances.

What is your tap water hardness? Is the 80-90 ppm GH in your tank before adding RO Right, or after? Are you adding anything to provide other trace nutrients?

RO Right contains nothing that will invalidate your CO2 calculations.


Roger Miller


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## imported_Austin (Nov 8, 2004)

Straight out of the tap its about 80ppm adding the RO right really hasnt made a huge difference from what I can see or test, im adding about 2 tbsp at water change.

My trace elements is from CSMB + extra Iron from Greg watson.


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## Roger Miller (Jun 19, 2004)

If you have 80 ppm of hardness in your tap water then you shouldn't need to increase GH. You shouldn't have to worry about calcium shortages and you shouldn't need to add RO Right.

That's about the same hardness I have in my tap water these days. I know from my water utility that the hardness includes very little magnesium, so I add a little magnesium sulfate along with each water change. I probably don't need to do that.

I am a little concerned about your potassium dose. Assuming that you're using potassium sulfate, 3/4 tsp every other day (say your tank has 40 gallons of water and you add it 3x per week) comes out to 40 ppm/week. There's also potassium in RO Right. Even if you're religious about doing 50% weekly water changes you could easily have 80 ppm of potassium in your tank. If your water changes are smaller or less frequent then the potassium concentration will be larger. You're also adding sodium with the RO Right and the baking soda.

What is your tap water KH? If your tap water gives you the 70 ppm you cited in your original letter then adding more is something else you don't need to worry about.

I haven't grown L. "cuba", but my experience with other Ludwigia suggests that they need more trace metals than many other plants. As I understand it, L. "cuba" is a fairly sensitive plant, so not a very good indicator of general conditions in your tank. How are other plants doing?

If you do need to increase GH then a mixture of calcium chloride (sidewalk deicer) and magnesium sulfate (epsons salt) will give a good result. Calcium carbonate dissolves slowly. Baking soda (sodium bicarbonate) is generally a good source for KH.


Roger Miller


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## imported_Austin (Nov 8, 2004)

Kh from the tap is around 50-60ppm i add baking soda to get to about 70ppm.

The tank is a 46 gal, I do religous water changes of 50-75%.

Your right I am using Potassium sulfate, I am currently dosing following the estimated index, here is a quick look at my dosing regime

Macros at water change the every other day after that, so fri, sun, tues at the following levels

3/4 tsp potassium nitrate
3/4 tsp postassium sulfate
2.5ml of phosphate ( 2 tbsp mixed with 250ml of water )

1 tsp baking soda
2 tbsp ro right

Micro is on the off days using plantex CSMB with the extra iron

15ml ( 1tbsp to 250ml of water )

All other plants I dont seem to see any other deficiencies, my stellata is growing great so far ( they were tiny plantlets now about 3" high ) glosso and H cuba are spreading quite nice crypts are doing well L repens is a nice orange/pinkish color ALt reinicki is growing tall and quite a dark red see the attached images ( just took some quick shot sorry for the low quality)


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## imported_BSS (Apr 14, 2004)

Hmmmm. So what's the problem? Plants seem to be doing well. THe tanks looks quite nice. Why are you trying to tweak the hardness?

I'm missing something,
Brian.


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## Roger Miller (Jun 19, 2004)

Brian's right. Your tap water GH and KH are great. You don't need to tweak them. 

Your plants look fine, except for the L. "cuba". From the overall appearance I wonder if maybe your light levels are a little low for some of the plants you're trying to grow.

Your potassium dosing is out of line with the EI recommendations of 20 ppm. You are adding 40 ppm/week from potassium sulfate plus another 33 ppm/week from potassium nitrate. With 50% water changes those doses could build up as high as 146 ppm. Your water hardness may be high enough to avoid problems from such high doses. Or it may not be. That seems to depend on the plants you are growing.

Your tank conditions will be closer to the standard EI recommendation if you cut potassium sulfate entirely out of your dosing regimen.


Roger Miller


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## imported_Austin (Nov 8, 2004)

Lighting I dont think is a problem I have 192 watt CF over the tank currently.

As for dosing I must be misreading something, if i follow the estimated index from what I have read using chuck gadds calculator

3/4tsp dry of NO3 adds 14.8ppm of nitrate
3/4tsp dry of K along with what K i get from NO3 equals about 20ppm
2.5ml of PO4 bring me just above 1 ppm

Assuming nothing gets used up I can see how the levels would get very high after second dosing and by the third dose really high, when i test on my off day or after water change everything seems ok.

I do know near to the end the levels are a bit elevated but using estimated I thought water change and uptake would keep everythign in check, algae has all but gone from the tank I dont even get any spot algae on the glass right now.

If you have any suggestions on tweaking the dosing regime or correcting it I am all ears, I f I dont have to play with the KH or GH thats a bonus my only concern is the melting or curling of the ludwiga cuba.

I took some better shots this morning.


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## Roger Miller (Jun 19, 2004)

> Lighting I dont think is a problem I have 192 watt CF over the tank currently.


So light isn't a problem







Maybe it's the white balance. My comment was based on the color of leaves and the same effect can be created several ways.



> As for dosing I must be misreading something, if i follow the estimated index from what I have read using chuck gadds calculator
> 
> 3/4tsp dry of NO3 adds 14.8ppm of nitrate
> 3/4tsp dry of K along with what K i get from NO3 equals about 20ppm


The guideline in EI is that the concentration of potassium in the water should be 20 ppm. Given your numbers above you are *adding* 20 ppm to the tank 3x a week. There's also potassium added with your water changes, potassium in fish food and potassium in the RO Right that you have been adding.

From Chuck's calculator, three quarters of a teaspoon of KNO3 in 40 gallons of water gives 11 ppm of potassium. Three quarters of a teaspoon of potassium sulfate in 40 gallons of water gives 13 ppm of potassium for a total of 24 ppm per dose. Three times a week gives you a weekly dose of 72 ppm.



> Assuming nothing gets used up I can see how the levels would get very high after second dosing and by the third dose really high, when i test on my off day or after water change everything seems ok.


What are you testing that seems OK?

If nothing is used then concentrations are very high. Of course, something will be used, but use isn't very important if your dose is way bigger than the use. Overall potassium consumption is not likely to exceed nitrogen consumption over the long run, so you can use the nitrogen consumption as a measure of how much potassium is probably being used.

If your 10-15 ppm nitrate is after a 50% water change but before macro dosing then your aquarium is using up 14.4-24.4 ppm of nitrate per week, which is 3.3-5.5 ppm of nitrogen. If the 10-15 ppm nitrate is after your first macro dose then your plants are using 44.4-54.5 ppm of nitrate (which means that they are using more nitrate then you are adding with KNO3) and that equates to 10-12 ppm of nitrogen.

Assuming that potassium consumption is about the same as nitrogen consumption (in round numbers, consistent with plant composition) then you are still adding way more potassium then EI calls for. You add 72 ppm/week. If the plants use 3.3 ppm/week (the low end of the range) then 50% water changes will let potassium build up to 138 ppm. At the other extreme, if the plants are using 12 ppm then 50% water changes will let potassium build up to about 120 ppm. Your potassium dose is so far in excess of plant use that plant use really doesn't make that much difference.

I should point out that these calculations are very approximate. There are a lot of other possible considerations. Most notably; 1)fish food is a large additional source of nitrogen and 2) plants may use quite a bit less potassium than nitrogen.



> I do know near to the end the levels are a bit elevated but using estimated I thought water change and uptake would keep everythign in check


Large water changes place a limit on how high the concentrations can accumulate. In your case you are adding so much potassium that the limit that it can accumulate too is still high.



> algae has all but gone from the tank I dont even get any spot algae on the glass right now.


I'm glad to hear that, but I doubt that the extreme potassium doses have much to do with it. Very imbalanced nutrients can effect some plants. Other plants are less effected. The potassium level may be part of the problem with your L. "cuba", but I couldn't swear to that. All in all, the potassium level isn't necessarily a problem for you right now. The high dose is a waste of your time and fertilizer (which obviously you're free to use any way you want) but it could be a problem in the future for your fish or for plants that you might add later.



> If you have any suggestions on tweaking the dosing regime or correcting it I am all ears,


My suggestion (already made) was just to leave out the potassium sulfate dose.

Roger Miller


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## imported_Austin (Nov 8, 2004)

Thanks Roger, I think I follow what your saying.

To give you an idea on consumption, my last water change was last friday, since then I have had the initial dose after water change and two additional doses of macro's at the previous established numbers, currently my NO3 is reading as 15-20ppm.

What I am testing for is NO3, PO4 and Fe as expected there is a gradual increase throughout the week but unless my test kits are off nothing is reading at an extreme range.

I have been using the EI method for about 2 months, and I dont have a problem with running a little leaner as I would like to bring out some more color in my E.stellata among others.

If we are assuming that my GH and KH dont need modifying,and I cut out the R/O right would my current dosing regime then still add too much K?

I'll pose this question too you, I know there are infinite variables but lets say it was a clean slate, what would a dosing regime via yourself look like? just as an different perspective I know your saying leave of the K but overall what would it look like.

My new week is fast approaching as Friday is my water change day and I dont mind tweaking my regime at all.


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## Roger Miller (Jun 19, 2004)

> To give you an idea on consumption, my last water change was last friday, since then I have had the initial dose after water change and two additional doses of macro's at the previous established numbers, currently my NO3 is reading as 15-20ppm.


That implies either that something in the tank other than the plants is consuming nitrogen *or* that you have a high plant growth rate. An exceptional plant growth rate will do more to limit the potassium build up. I don't think it can eliminate it, because you are adding potassium in a ratio to nitrogen that is far higher than normally found in plants. Some buildup is inevitable.



> What I am testing for is NO3, PO4 and Fe as expected there is a gradual increase throughout the week but unless my test kits are off nothing is reading at an extreme range.


"Extreme" is such a flexible term. Compared to concentrations in natural water your NO3 levels are 5-10 times normal, your PO4 level is 20 times "polluted" levels and your iron level is high enough to be toxic to some aquatic life. By some standards that's all extreme. By EI standards that's all good.



> I have been using the EI method for about 2 months, and I dont have a problem with running a little leaner as I would like to bring out some more color in my E.stellata among others.


Tom Barr has said that lower nitrate levels bring the red out a little more. If you're using Tom's method then you're best off sticking with Tom's advice.



> If we are assuming that my GH and KH dont need modifying,and I cut out the R/O right would my current dosing regime then still add too much K?


Yes. I didn't factor the K in RO Right into the estimates, so removing it doesn't change anything. After wrangling with Tom over relative consumption rates he finally did agree with me that potassium nitrate alone provides as much or more potassium (relative to nitrate) than the plants are likely to need. That conclusion might be modified a little by the amount and kind of food you feed your fish.



> I'll pose this question too you, I know there are infinite variables but lets say it was a clean slate, what would a dosing regime via yourself look like? just as an different perspective I know your saying leave of the K but overall what would it look like.


 I don't use EI, so my dosing regime isn't relevant. To keep things in the realm of EI I would not dose the potassium sulfate, but keep everything else the same.

Roger Miller


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## imported_Austin (Nov 8, 2004)

Thanks again Roger

I was planning on tweaking or changing my dosing regime even considering a switch away from EI method, hence the reason I had asked about how you would do a dosing regime, but I realize the complexity and how there are so many factors that it would be difficult to just say this is what it would look like, basically looking for alternate regimes to try out and experiment with.

I sat back and thought about a few things and decided I will run the tank a little leaner as I am now trying to get some of the colors to come out a bit more vibrant, hopefully without stunting growth or causing an algae bloom.

Here is what I have come up with. Will try it for 3 weeks and see what the results are.

Cut out the RO right ( if deficiency continues will try magnesium sulfate as it seems consensus is its a mg shortage )

Keep the baking soda to keep KH at 70ppm

Water chane of 75% to reset tank and build up.

Dosing

Potssium Nitrate 1/4 tsp approx 5ppm of NO3 and 3ppm K
Potassium Sulfate 1/tsp approx 3.5ppm bringing total to 6.5-7ppm of K
Mono Potassium sulfate 2.5 ml approx 1ppm PO4

15ml CSMB+Iron approx 1ppm Fe

Dosing on alternate days as stated previously.

Over a weeks time depending on uptake, food and fish waste additions totaling

NO3 15ppm
K 19.5-21ppm
PO4 3ppm
Fe and trace 3ppm

First off does this regime appear more in line with the EI ( meaning I totally misunderstood it ) Second os there anything that jumps out as a imbalance or shortage? I am thinking the PO4 with a lower NO3 may cause an issue.

Thanks again


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## Roger Miller (Jun 19, 2004)

Austin,

I don't use or recommend any of the "systems" and I see no value in proposing another.

Systems like EI are starting points that people can use to get the routine they want. Most people who start with any of those methods and follow it long enough eventually tweak their routine to get something that works better for them -- which is just the process you're starting now.

Your suggested dose might work fine, but I think you will be better off if you get to it gradually, rather than cutting it so much in one step. I'm particularly concerned about the big cut in potassium nitrate. From your earlier letters it looks like you have a lot of nitrogen uptake. If you simply cut nitrate additions back to less than the plants are currently using then the result may be poor color, leaf loss and algae. I suggest that instead of cutting it back so much that you should set a goal of having no more than 10 or less than 5 ppm NO3 in the tank through the course of a week. Gradually reduce your nitrate dose to maintain those levels. Once you get there then you can adjust your other doses in proportion.

I would still avoid the potassium sulfate. That recommendation will not change.


Roger Miller


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## imported_Austin (Nov 8, 2004)

Cheers thanks for all the help Roger I really appreciate it.

I woke up this morning looked at the tank and looked at it as a whole and not just one plant, I think I will drop the NO3 a bit as you say to no more than 10 gradually and cut out the K until I see a defieciency if ever.

The L cuba this mornig looks 100 times better and growth seem to have come out of nowhere so something must be right. 

Enjoy the pics


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