Ro or rodi water

[King puff]

the taps tds is 540 and yet the gh and kh still seem unusually low

 

[seangee]

I'm with @AbbeysDad here. Stick with tap water unless you have a reason not to. I mix RO with my tap water to reduce hardness (and don't add minerals back). You don't seem to have any need.

 

[King puff]

Ok! Doing all this would probably make things worse. The tank I’m thinking of doing it to looks really nice so I don’t want to mess it up

 

[Byron]

Given the GH of your tap water, I agree with others that there is not much value in not using it for your fish.

It may help to explain a bit about TDS, following up on what Colin summarized in post #15. I have never tested for TDS because the GH and KH of my source water are very low, less than 1 dGH or 1 dKH, and the mineral content (the GH) is what matters most to fish; some must have it, others should not. The pH follows the GH/KH.

Total Solids basically refers to organic and inorganic matter that is either suspended or dissolved in the aquarium water.

Total Suspended Solids (TSS) refers to the amount of solid waste, decaying fish and plant matter, etc. that can be captured and held by a filter.

Total Dissolved Solids (TDS) is a measure of the combined content of all organic and inorganic substances contained in the water in molecular, ionized or micro-granular (colloidal sol) suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a sieve the size of two micrometer.

Fresh water by definition contains no more than 1500 mg/l of TDS. Brackish water contains 1500-5000 mg/l, and marine (salt) water has more than 5000 mg/l of TDS. Note that mg/l is basically equal to parts per million (ppm), and also that this is not suggesting a level of 1500 ppm in an aquarium; these are just the approximate figures for the three categories.

TDS is connected to GH (general hardness) because like GH, TDS includes the calcium, magnesium and other “hard” mineral ions; these ions are what we measure with our GH test kits. But water hardness correctly considered is more than this; both GH and KH can affect hardness and TDS levels; however, the reverse is not necessarily true. Aquarium water can have a high TDS level but a low GH and KH (Jensen, 2009). The TDS for instance also includes sodium (salt) ions, chemical substances, etc. which are not reflected in the GH.
TDS is basically everything dissolved in the water: chlorine, chloramine, ammonia, phosphate, salt, hard minerals (GH), bicarbonates (KH), etc. And almost every substance added to the aquarium water will increase TDS: water conditioner, fish foods, plant fertilizers, calcareous substances, medications, water adjustment products, etc. Another reason not to use non-essential substances/additives.

 

[King puff]

Thanks for the help! Very informative!