Striving to know my tap water

[rdaled]

So I have done a little research to learn what exactly is in my tap water. The issue that has prompted this is consistently higher nitrates, neutral pH and very low Kh and Gh. Visible symptoms include algae growing on leaves of slow growing plants. Here is what I have found...

Tap water API tests: pH 7.0, nitrates 5, Kh 2, Gh 2

 

Here is some information I found online regarding our municipal tap water...

"The Salisbury-Rowan Utilities’ Water Treatment Plant uses a pretreatment process called Actiflo, which is a high-rate clarification unit. Micro-Sand, Polymer, and Poly-Aluminum Chloride are added to the raw water as it enters the pretreatment units to begin the coagulation process. After mixing, the solids are removed by the pretreatment process. The water is allowed to settle up to 4 hours and then it is filtered. After filtration, Sodium Hypochlorite, Fluoride and Phosphate are added and the pH is adjusted using liquid lime. Fluoride is added to promote stronger teeth, and Phosphate helps to prevent pipe corrosion in the distribution system. Solids that are removed from the raw water are de-watered and eventually reapplied to farmland in Rowan County."

 

So according to the attached chart...

Alkalinity 24.3ppm = Kh 1.3

Hardness 24.5ppm = Gh 1.5

 

What I need to figure out is how to raise Kh and Gh, or add more minerals to my water, without raising my pH. I read that crushed coral will help, but won't that raise the pH as well?

 

Edited December 20, 2020 by rdaled

[AdamTill]

Generally pH and KH are strongly coupled, so raising one without the other will be difficult. GH can be raised without adding carbonates, so can be done at the same pH.

Why would a slightly higher pH be a problem?

Edited December 20, 2020 by AdamTill

[rdaled]

Isn’t a low KH and Gh an indication of a lack of minerals needed by live plants? I feel like if I had better growth rates from my plants then they would be better able to utilize the nitrate and out compete the algae. 

[pedrofisk]

I've used Seachem Equilibrium to provide minerals for my plants as my tap water is almost RO it has so little mineral content.

[AdamTill]

38 minutes ago, rdaled said:

Isn’t a low KH and Gh an indication of a lack of minerals needed by live plants? I feel like if I had better growth rates from my plants then they would be better able to utilize the nitrate and out compete the algae. 

0KH and GH would be, yes, and likely would mess with your filter. If you still have 2KH at the end of a period before you change water you’re fine though.

You can add more, and you’ll likely get a slightly higher pH, but again I wouldn’t be worried about that either.

[rdaled]

Thanks @AdamTill 

So if prior to a weekly water change I still have a Kh and Gh of 2 then I guess it makes sense that the plants aren't running out of essential minerals. 

[AdamTill]

In a nutshell, yep

[rdaled]

Having an open top aquarium and lots of surface agitation I get a lot of evaporation. Because of this I have an auto top-off system that replaces evaporated water. Up to this point I have simply used dechlorinated tap water in my top-off reservoir, which has a nitrate level of 5.

I'm now thinking that it would be best to fill my reservoir with RO water since that is basically what evaporates from the tank. Constantly topping off with tap water that has nitrates is only going to increase my nitrate levels.

Hopefully this will help curb the algae.