# Setting up substrate for soft water



## JT_ (Jul 23, 2010)

I was reading thru an article from this forum “Setting up a Walstad Natural Planted Tank” and it says: “If you have soft water add pelleted dolomite lime, or crushed shells to gradually increase the level of hard water nutrients over time”. 

I’m setting up a 46 gallon natural planted tank. I have already acquired a bag of miracle grow organic choice potting soil, as suggested in Diana Walstad’s book. I also got inert gravel. The thing is I’m concerned about my water (city water) being soft: kh_3, gh_3, tds_74, ph_7.6, so I’m considering additives for the substrate. The other thing is that the ph in my other much smaller (gravel only) planted tank always stays stable (at around 6.7ish) so I don’t know if I have a problem yet, however this is my first time using soil in a tank...

Anyhow, I was thinking of mixing in some crushed coral. I’m putting together an online order for something else, and that vendor sells that, and I could roll it into the same shipping price, so it would be convenient, but would it be effective? It’s crushed coral with aragonite “which provides up to 25 times the buffering power of other crushed corals, dolomite, or oyster shell”. Would this be an appropriate substrate additive for my situation? I could set up a few mason jars for testing, but if I go through the effort and expense, I just wanted to know I was on the right track… 

Wondering how much to add? I’m guessing the total substrate volume to be 3 gallons of soil, and say 3 gallons of inert gravel. Would the additive get mixed into both layers, or just the soil layer? 

The other method that I was considering was to add it into a basket of my canister filter (then I would have the option of taking it out if there were any issues). In that case would the coral do double duty as a bio filter or does the filter media have to be totally inert for bio filtering? 

Any advice?


----------



## gpodio (Feb 4, 2004)

I've had soft KH2~3 GH4~6 tap water for the last 10 years and have been quite happy with it... I've used baking soda to raise KH and Seachem Equilibrium to raise GH when I wanted to but haven't had any reason to do so other than to experiment/play purposes. My PH is around 6.6~6.4 depending on CO2...

If it were me I probably wouldn't add anything that can't be removed if needed. Having come from hard waters prior to this, I must say I prefer a soft water tank...

When I have used crushed shells, I asked a local restaurant to put aside some oyster shells for me which I crushed and placed in media bags in the canister filter. It should indeed become part of your biological filtration as it's surfaces become living space for bacteria... Not sure what you will find at an aquarium store other than calcium reactor media, which should work but can be expensive.

Hope that helps
Giancarlo Podio


----------



## Michael (Jul 20, 2010)

You can also buy oyster shell from a feed store. It is sold as a calcium source for poultry, and it is very inexpensive.


----------



## JT_ (Jul 23, 2010)

Thanks for the advice and info.

I think I'll look around/shop around for additives, and add them to the filtration system as necessary.


----------



## ILuvMyGoldBarb (Apr 7, 2007)

When I was setting up my tank I ran into the same issue of soft water. Out of the tap min is <1 dKH and <1 dGH. My TDS is only 14 according to my meter. There was nothing in my tap water for my plants. I was advised by Diana Walstad to add bone meal to my substrate. This has proven to be quite effective. In spite of my ultra soft water my plants show no sign of calcium deficiency at all.


----------



## JT_ (Jul 23, 2010)

Thanks.

Bonemeal sounds like a good additive. I think I even have some out in my shed . Do you remember around how much you added?


----------



## ILuvMyGoldBarb (Apr 7, 2007)

I used 1/2 tsp/qt soil upon recommendation. It seems to have worked quite well for me. It is quite concentrated so you don't want too much.


----------



## Diana K (Dec 20, 2007)

Whatever you think will work, get a small amount and test in jars. 
Set up one jar with just your soil. Then other jars with the other materials you want to test:
Put in a measured amount of one material per jar, a handful of your soil and a measured amount of water in a jar and monitor pH, KH, GH and TDS for at least a week, perhaps longer, if you will be trying to stretch out water changes to monthly or less frequent. 
Think about how these will affect the tank:
Is the change gradual? Then you will want to set up water changes ahead of time, so the new water will match the old. 
Is the change stable? Once it reaches a certain point does it hold there?
With the soil in the jar it will be more like what you will see in the tank. Some materials in the soil may react with the minerals you are testing and make the situation more stable. I would run the tests out for at least 2 months, or start with soil that has already been under water for a month. 

In general, I prefer adding these materials to the filter. You can change the recipe a lot easier than if they are in or under the substrate. 

The exception is when it does not matter how hard the water gets. In my Lake Tanganyika tanks there is coral sand in the substrate. GH, KH, TDS and pH hold very stable in the range prefered by these hard water fish.


----------



## JT_ (Jul 23, 2010)

Thanks.

I’m leaning towards doing some testing for choosing the material to add to the filtration system. To emulate that set up in an experiment, would it make sense to “tea bag” the material in a nylon filter sock, within the mason jar? (I have some 100 micron socks). 

So, I guess the goals are speed and stability, as the material is mostly common and inexpensive. 

I was hoping to get upwards of 9 kh or 10 kh, with a ph ~7-7.5 to accommodate a trio of swordtails. Now, I have a pair of pearl gouramis whom the tank is intended for (I need more space to accommodate the male's attitude issue:mad2. The gouramis seem to tolerate the lower ranges to mid high. I was hoping to get it in the middle of each types preferences. From what I gather, my plants prefer medium soft water.


----------

