Confused about TDS results

[Bremenguppie]

So i drained most of the water out of my tank that was filled with tap water and filled it with water i ran through my rodi system. I used my tds meter and it showed 0. I mixed up my water w salt and it was with in levels its suppose to be. Ive still having a bit of a brown algie break out which i figure is just remaining in tank from tap water. I take a cup full water from my tank and test it with my tds meter and it goes off the charts and errors out cause its to high. I check the meter under tap water and it reads at 900 tds so i knpw its working right, but i dont understand why its going crazy with the salt water. Does salt water affect those meters?

 

[lpsouth1978]

There will be a TON of dissolved solids in salt water. The salt alone is a dissolved solid, plus there are many other minerals and such in the salt mix. There will be TDS after adding the salt, so measuring this is totally useless. As lond as the Water from the RO (before Mixing with salt) is at or near 0 you will be fine.

As for the brown algae, this is 100% normal for a new system and may only be diatoms as well. as long as your levels are where they should be, this will run it's course and go away on it's own. Just a part of the "uglies" associated with new tanks.

 

[nereefpat]

I agree with everything above.

FYI, saltwater is about 35 parts per thousand. This would be about 35,000 parts per million.

 

[mcgyvr]

Yep... A typical TDS meter is NOT for measuring saltwater.. Fresh water only.. All of that salt is a "dissolved solid"..
A refractometer or hydrometer is what you use to determine the salinity of your saltwater..

 

[Bremenguppie]

Thanks guys. Thats kinda what i was thinking with the wacky readings i was getting

 

[hkgar]

Welcome to reefing - keep on learning! And, asking questions.

 

[Daddyrawg]

That's why when you use the same jug that you used water changes with, then empty it out and use same jug to fill rodi with o tds then test your water you will get elevated readngs like 35 or 40 becasue of the left over salt from the previous jug you used for saltwater change..

 

[hkgar]

Get on of these and measure your water out of the RO membrane and out of the DI cartridge.

https://www.bulkreefsupply.com/dual-inline-tds-meter-dm-1-hm-digital.html