Filling My Tank for the First Time TDS Issue

[Chris H Reef]

Hey All,

I'm filling my 75 gallon for the first time with RO/DI water I am making myself. I have dry rock and live sand in the aquarium. The sand said not to rinse so I poured it straight in from the bag.

The issue that I'm having is the water coming out of my RO/DI is showing 0ppm, BUT now that the water is in my aquarium it is showing 369ppm. I have the tank about 75% filled so i'm not running the sump or any filtration yet. The tank water is still fairly cloudy but clearing up. Is my high ppm because of the cloudy water? Will it go back down to 0ppm after the water clears up?

 

[piranhaman00]

No it won’t. You are picking up tds from the sand and rock. It’s no problem , should have mixed the salt into the water before dumping into tank.

 

[RocketEngineer]

To be clear, TDS only is important for the water leaving the RODI unit. It’s an indication of how close to pure water you are getting. As soon as you add salt to it or add it to the tank with sand/rocks present, it’s going to dissolve the salts and minerals present and is therefore no longer pure water anymore. Since we are trying to make salt water, this isn’t an issue. We now need to use other methods to measure things like salt content and mineral concentrations.

 

[Dmmz]

You are fine if it was reading 0 before adding it to the tank

 

[Chris H Reef]

Thanks everyone for the clarification! I had a mini heart attack thinking I was going to have to make 75 gallons of rodi water again!

 

[Dom]

Thanks everyone for the clarification! I had a mini heart attack thinking I was going to have to make 75 gallons of rodi water again!

TDS = Total Disolved Solids.

Measuring water from the output of the RODI system is zero, so you're good.

The reason your TDS is 369 in the tank is because of everything in the tank. If I put my TDS probe in my tanks, it would read 9999.