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TDS in RCS tank...HELP

1637 Views 6 Replies 4 Participants Last post by  en7jos
This is my first post on here, but I've learned a ton lurking around already, so let me say thanks for all the help!

To start, I have a 20gal tall tank that's been up and running for about 5 months now, ADA amazonia sub, Finnex Planted + 24/7 LED light that I run for 9 hrs/day (only a few hours of full light), canister filter with sponge on the intake, moderately planted, some dragon stone and one piece of driftwood. No CO2, dose ThriveS 3x/week (4 pumps at a time). I have, about 7-12 RCS (they're hard to count all at once) that have been in there for almost 3 months and I feed them 3x/week a very small amount of either powder or shrimp specific dry food. Only other fauna is some snails that hitched a ride on my plants.

Parameters: No ammonia or nitrites, nitrates at about 10-20 (very hard to distinguish with the API master test kit), pH has always been holding at the 6.0 level, GH of 4-5 degrees and KH of 0-1. I'm guessing my substrate is constantly buffering and I don't try to fight it. I just got a TDS meter last week and my initial reading was 279. From what I've read across multiple sites is that's on the higher end although it seems like there's constantly exceptions out there of people having success at the extreme ends.

I just installed an under the sink RODI filter and have done 2, 20% water changes so far this week. I remineralize with salty shrimp GH+ to get some stuff back in the water so my new water has a TDS of about 80, with the goal being to bring down my tank's TDS.

My question is this-what should I shoot for in terms of TDS/GH/KH/pH. What should my target TDS be given my GH, KH, and pH. Should I try to lower the pH of my new RODI water to match my tank water? My shrimp are active, eat, and swim around, but no breeding or babies yet.

Am I overthinking this? I feel like I am. I just want those little guys to be happy and have a nice tank for them.

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Discussion Starter · #5 ·
Thanks for all the replies. Exactly the info I was looking for! I feel like I can finally wrap my head around TDS. Disclaimer: Before getting the RODI unit, TDS meter, and salty shrimp GH+, I was adding seachem equilibrium to my tap water to get a GH of 5. I wonder if my tap water plus the seachem equilibrium is why my tank has such high TDS with a GH of 5 and KH of 0-1.

Great advice on doubling the amount of water to test GH and KH where each drop is .5 degrees hardness. I will do that from now on.

About my pH...should I lower the pH of my new water during a water change so it's closer to tank water's pH? I have seachem acid and alkaline buffers. Also, is there any test out there to find out what my actual pH is since it could be below the 6.0 limit of my test kit?

Here's my plan going forward. Let me know if there's anything off about it:

1) Calibrate my new TDS pen
2) Do smaller water changes (10%) with RODI water and remineralize with salty shrimp GH+ to get 7 degrees hardness and a target TDS of the new water of 150 (after letting the stuff dissolve for a while).

Thanks again. This forum rocks.
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