Advantage of RO or rain water?

[Matuva]

Hi all,

Yesterday, for the first time, I used a remineralizer (GH Builder) to to upgrade my rain water before water changes. The rain water has a very low TDS, around 8, so it is perfect to lower TDS levels in my tanks.
From what I understand, I must remiralize, if not, these waters are not suitable.

So, I started with rain water, KH, GH, NO², NO3 = 0 Yada, yada.... TDS is 8.

I dosed the GH builder accordingly: 1ml per 3 liters to raise GH 0.5>1 GDH. I dosed to achieve a GH at 4. Then, I measured TDS, and found it up at 170

Prepared another bucket with rain water, started at TDS 8 and reached TDS 165 with the new mix

Is that something normal? I'm complying to all instructions of this GH builder to dose...

Under those conditions, with a TDS sky rocketting, I don't see any advatage to bore with rain water or RO for water changes - other than seeking for a 0 KH - considering my tap water is KH 3, GH 5, TDS 70...

What's your TDS once you have remineralized it?

Edited February 15, 2017 by Matuva

[jayc]

I'm confused what you are trying to do or what water parameter target you are trying to reach.

Premixed remineralisers are meant to do that.

 

The RO or rainwater with remineraliser that has a TDS of 170 is made up Calcium & Magnesium.

VS

Tap water TDS of 70 that is made up of ???????

Knowing exactly what is in your water is the key benefit.

If you need TDS lower, but GH still at 4, then you will have to make your own remineraliser.

That product you have is made to give ~165 TDS at GH4, based on the amount of Ca and Mg they used.

[Matuva]

My target is to maintain low TDS in my tanks, 2 especially, the one with CRS, and the second hosting local shrimps caught in the wild.
In the wild, parameters are KH: 0, TDS 30~40, GH unknown (3 according band test). For this one, I think a remineralized water with a TDS of 165 should not comply, considering the wild water is at 30~40. Should I just use rain water with nothing else?

For the CRS tank, I would like to bring the TDS level back from 235 to 130, so, in that case too, a water with a TDS of 165 is not going to do the trick.

I ended using pure rain water to reach my goals, I'll see what's going on.

As for my tap water, Kh: 4~5, GH 4, TDS 70

[jayc]

6 minutes ago, Matuva said:

For this one, I think a remineralized water with a TDS of 165 should not comply, considering the wild water is at 30~40. Should I just use rain water with nothing else?

Yes, just plain rain water should be used. You could add a very little amount of remineraliser to bring TDS up to 20-30. But only if you want.

 

7 minutes ago, Matuva said:

For the CRS tank, I would like to bring the TDS level back from 235 to 130, so, in that case too, a water with a TDS of 165 is not going to do the trick.

You still use the remineraliser for rain water to bring it up to TDS130. Just use less.

[Matuva]

Thanks for advices Jayc. I though I must absolutely remineralize rain or RO water, but doing that way makes things easier.

So, if I correctly understand, for water changes (from 10 to 25% of tank):

- for the "wild" tank, rain water is fine, remineralizing recommended (up to TDS 20~30) if big water change, just topping is OK

- for the RCS, topping with "raw" rain water is OK, but if big water change, remirelazing is recommended.

[Zoidburg]

Is the GH Builder liquid or powder?

 

Correct though.... top off - RO or rain water. Water changes, remineralize.

 

 

For lowering TDS in a tank, there's a few different things you can do...

Remineralize new water to desired TDS and perform more frequent water changes.

Remineralize water to a lower TDS (i.e. target is 130, remineralize to 100), and use this water until the target TDS is desired in tank. Switch back to higher TDS water at next water change.

Use straight RO/DI or rain water. Not recommended, as this could result in a much more drastic change and cause shock to the inhabitants.

 

 

As per a couple of other forum members, your tap water TDS should be around 150.... nice to see someone else with low TDS tap water. I have 3 KH and GH with a TDS of ~50. I've been mixing it with hard water, about 4:1 ratio, and aim for about 180 TDS.

[jayc]

2 hours ago, Matuva said:

So, if I correctly understand,

As Zoidburg has already confirmed, yes, you can use straight rain water for your wild tank, much like our Zebra shrimp here, that like very low TDS.

For RCS, CRS and fish, you will need to remineralise to a suitable TDS level.

[pastu]

i use salty shrimp gh + to remineralize my 2 tds ro water and achieve gh 4 at a tds of 60-70 and that is what i use for water chánges.  Tds in the tank stays arround 90 to 100. .for Taiwan bees. Good breeding and baby survival