# (Very) Hard Tap Water



## k-maub (Feb 10, 2007)

I am currently using the EI system, and I have come to believe that weekly water changes are not entirely beneficial to my tank. That is, my tap water is very hard (calcium carbonate ~233, TDS ~300 according to my water provider), and while I've seen the kH drop from 13 to say nine degrees in between water changes, each water change restores the consumed calcium carbonate.

My concern is that I am not always the most diligent water changer, but when I am on top of things, I notice that a whitish film forms on some of my broad-leaved plants (esp. amazon sword). The algae (and no matter what I do, there is always some) tends to skew towards other broad-leaved plants (e.g. crypt wendtii, temple), and tends to be a darker, "harder" GSA when water changes are more frequent.

A few questions: Am I connecting the dots correctly that these high calcium carbonate concentrations could be problematic for me? Do I have an alternative while still sticking to some form of EI (which I have otherwise been very happy with)? Has anyone else developed any coping strategies to deal with very hard tap water (short of using reconstituted RO water)? My only thought is to buy an TDS tester and check the overall TDS levels periodically, conducting water changes when the TDS gets to an "unacceptable" level.

Some tank parameters if they can be helpful: 30 gal. tank, 12 hr/100 watts, 13 deg. kH, 7.2 pH, ~25 ppm nitrates, heavily stocked


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## Avalon (Mar 7, 2005)

Are you having any other issues with your plants such as a lack of growth, leaf curling, additional algae, etc? I used to grow plants in very hard water and my main issues were the KH & CO2 levels. If I had my druthers, I'd try to keep the KH below 10 because it just makes getting more CO2 dissolved into the water much easier. I suspect that when you raise the KH with your water changes, you are effectively reducing the concentration of dissolved CO2 in the water, hence the GSA.

You can certainly reduce your water changes, or even make smaller ones. You may need to adjust the amount of your fert dosings (not frequency) as overall levels will tend to build up quickly using the EI method. I'm hesitant to speculate on the white film on your plants though. TDS readings will be the least of your worries. Your answer lies in the KH & CO2. You can reduce your KH, or you can improve your CO2 dissolution method (the mist method works well in hard water) to get more CO2 in the tank.


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## SnakeIce (May 9, 2005)

Have you done experiments with Mg to see what the levels are in your water? I have water about half that hard and have about 50 ppm Ca and less than 2ppm Mg and 70 ppm of hardness that is not either of those two. I dose some Mg or I don't get growth.


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## k-maub (Feb 10, 2007)

Won't dosing Mg just make my water harder? Or does it not matter as much, because I'm raising Gh, and not Kh? Anyway, there should be some in the Plantex I add. Maybe that's not enough?

Avalon, what is the "mist method" of injecting CO2? I'm currently just using a typical tube reactor where the bubbles come up against the flow.

I'm having fewer leaf-curling in new growth now that I spread out Plantex to every day (I read something TB said about how hard water locks up the micros quickly so they can't be used).

The algae I'm seeing more of is a really dark green film growing on my broader leaves (in addition to the green dust; no my phosphates aren't low) that resembles green spot in texture and adherence if not all that spotty.


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## rs79 (Dec 7, 2004)

The white coating is a carbonate build up from biogenic decalcification. The plants are eating the water hardness. When it goes from 14 to 8 where do you think it's going? What you see is a byproduct of this reaction. 

Add Co2 or flourish excel to stop it from happening. It's mentioned in the Dupla book.

I have very hard water and get this in some tanks. 

Barr points out for no co2 and hard water you can just top up the tank without changing water given a moderate bioload. I'd noticed that too. I'll admit my guilty secret and say I have one tank in particular that I've just topped up for years and it's fine.

Richard


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## Bert H (Mar 2, 2004)

Keep in mind there are 2 types of 'hardness'. One from the carbonates in the water (kh), the other from the levels of Ca and Mg (gh). I, also, have hard water (kh10, gh13), most of which comes from the CaCO3 (calcium carbonate) dissolved in the water. If I don't add Mg, I get all sorts of stunting issues with many stem plants.


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## k-maub (Feb 10, 2007)

Wow! Lots of great info. A few follow up questions if I may...

RS79, did you mean to say that Barr suggests HIGH CO2 and hard water requires just topping off? Otherwise, with low CO2, presumably I'd need to scale back my light, ferts, etc. Sounds like a low-tech tank at that point.

Also, I was hoping the calcium was being consumed by the plants and integrated into their growth. But you are suggesting that the film is a precipitate resulting from the plants taking up other nutrients? I'm curious, does the book indicate how additional CO2 would retard this process? I can certainly bump up my CO2 output if that would help, but I'm curious as to the mechanism at work.

Bert, do you add Mg above and beyond the amount that gets dosed as part of your micros (i.e. as part of normal Plantex dosing)? I have MgSO4 that I can dose separately if more is needed. I have already noticed less twisted, new growth now that I am dosing Plantex everyday, though.

Great info, everyone. Thanks a lot!


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## hoppycalif (Apr 7, 2005)

Tom Barr recommends not changing water if you don't add CO2 to the water. That is because tap water contains CO2, so everytime you change water you are increasing the amount of CO2 in the water temporarily, but it then drops back to a very low amount. This fluctuation in CO2 encourages algae to start growing. But, if you just top off the water to replace evaporated water, you don't add muchCO2 at all with the tap water. To follow this method you also don't dose much if any fertilizers, since the lack of much carbon means the plants are not going to grow fast anyway, and of course you want only low light intensity for the same reason. In other words, an el natural tank.

If plants grow they are using carbon from some source, since most plant tissue is carbon. If you aren't providing CO2 for the plants, carbonate is the next easiest to get source of carbon for the plants. So, they take the carbonate from the water, leaving excess calcium behind, which precipitates out. Right, RS??


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## k-maub (Feb 10, 2007)

That, hoppy, is a very good explanation that makes a lot of sense. I now know why that film was much worse before I switched from DIY to pressurized CO2.

Thanks so much! Now I just need to get my cories healthy...


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## Edward (May 25, 2004)

Bert H said:


> Keep in mind there are 2 types of 'hardness'. One from the carbonates in the water (kh), the other from the levels of Ca and Mg (gh). I, also, have hard water (kh10, gh13), most of which comes from the CaCO3 (calcium carbonate) dissolved in the water. If I don't add Mg, I get all sorts of stunting issues with many stem plants.


 How high is your Ca in ppm?


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