TDS meter confusion...

WTFish?

Active Member
#1
Just got my first tds meter in, my tap is 221, my 10g is 289 and my 5g SHRIMP tank is 471! What? Wondering how they can all be so different and what I can do for shrimp, although they seem to be thriving I believe anything over 250 is bad...thanks for any advice!
 

Brookster123

Resident nuisance/moderator
Staff member
#2
Total dissolved solids. Could be anything really. Anything added to water has the potential to raise tds. Ferts, food, supplements, substrate and rock can leach. It's not all bad. As long as the inhabitants seem healthy and eat well. It's really a major concern when breeding certain fish and keeping certain wilds. Don't tell anyone but I use my tap water for discus and right now it's 400... shhhhhh
 

FishFlow

Well-Known Member
#3
Haha. Don't be scared!

http://praquatics.com/forums/threads/lets-talk-tds.2706/

Poppa's thread does a good job of the definition of TDS.

In relation to your fish tanks.. Currently, my biggest take away, Fish do not like sudden, large swings, including TDS. I have one tank that was only getting top offs for some time. The TDS # is now much higher than my tap. In that tank I am doing smaller WC weekly to bring the TDS # back down closer to my source water TDS #. (Slowly over time.) Vs a 90% WC which would be a large swing.

I do not know what a large TDS swing is though.. (Still learning over here)
 

WTFish?

Active Member
#5
Thank you both, read that article FF...interesting for sure but yeah, still so many questions. I was using half ro water in the beginning when my adults were dying (they came from soft water, mine is hard) I quit that when I had babies (rcs) so they would be raised in my tap...thriving for sure.
 

OnTheFly

Well-Known Member
#6
That is a wide disparity in readings. Does your meter consistently measure RO at zero or at least very low? 250ppm is not automatically a bad number for many species. I use TDS to determine relative change in my tanks after monitoring them for awhile. I don't obsess over it, but if one tank starts climbing much higher than the rest it gets a bit larger WC.
 

WTFish?

Active Member
#7
That is a wide disparity in readings. Does your meter consistently measure RO at zero or at least very low? 250ppm is not automatically a bad number for many species. I use TDS to determine relative change in my tanks after monitoring them for awhile. I don't obsess over it, but if one tank starts climbing much higher than the rest it gets a bit larger WC.
Hi, my ro bottle of water was 26, but also very cold....I’m guessing heat is a major factor.
 

OnTheFly

Well-Known Member
#8
Hi, my ro bottle of water was 26, but also very cold....I’m guessing heat is a major factor.
26 is high for RO. Maybe test again warm, or test the meter on some distilled water. My RO unit filters are getting some age to them so RO measures about 5 now. Ice cold out of the faucet.
 

WTFish?

Active Member
#9
26 is high for RO. Maybe test again warm, or test the meter on some distilled water. My RO unit filters are getting some age to them so RO measures about 5 now. Ice cold out of the faucet.
Oh I should clarify, it’s purified drinking water bottle, but says purified by ro, not a unit....but I’ll warm some and try again...
 

OnTheFly

Well-Known Member
#10
Oh I should clarify, it’s purified drinking water bottle, but says purified by ro, not a unit....but I’ll warm some and try again...
It may not be real RO in the first place. A lot of drinking water will not test 0. Your results aren't going to mean much.
 

WTFish?

Active Member
#11
Ok, so now warm purified water is 59, my 10 is 339 and my 5 is 413, but 5 minutes ago it said 461....maybe this meter is not so awesome?
 
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