GH and water params

[Nemo2182]

Hi guys.

So I started doing 1 part RO to 3 part tap water since doing my rescape, but am shocked to find it has only come down two degrees on the chart....I was hoping to take it down at least 100ppm. Currently I am at 268ppm, but need to be closer to 200ppm for a balance for what I keep. Unfortunately being new to the hobbie, I chose two types of fish at different ends of the chart annoyingly. Guppies like hard water and Corydora Habrosus like soft.

Should I start 2 RO to 2 Tap? Or will that be a two big change for the inhabitants? Im also conscious I have Cherry Shrimp and a Zebra snail which also like a bit harder water....

 

[mbsqw1d]

Test the 2:2 ratio in a separate bucket and see where you get up to and once happy start applying that to your next water changes. Probably for the best that you've got it slightly higher than your target as this will make for more of a gradual change.
What substrate and hardscape do you have? Are you certain it is all inert?

 

[Nemo2182]

Test the 2:2 ratio in a separate bucket and see where you get up to and once happy start applying that to your next water changes. Probably for the best that you've got it slightly higher than your target as this will make for more of a gradual change.
What substrate and hardscape do you have? Are you certain it is all inert?

I made sure sand was, but I do not know if knife rock is? I use a fair bit of that, even to make different levels in the sand. I only use live plants and have a 30cm bonsai tree.

 

[mbsqw1d]

I made sure sand was, but I do not know if knife rock is? I use a fair bit of that, even to make different levels in the sand. I only use live plants and have a 30cm bonsai tree.

Hmm I'm not familiar with knife rock..
All i could find is

Knife Stone per KG

Grey stone for small aquariums and Terrariums. Ideal for building small stone arrangements with only 3 or 4 stones. Colour ranges from light to dark

www.aquariumgardens.co.uk

And in the description it says 'gives little calcium'.. which suggests its not inert (I doubt any rock is 100% inert?), but it will certainly be working against you in trying to lower your gh.
I'd experiment a little. remove a small piece of the rock and place in a bucket with some RO water. Measure gh before and after and then you can knw whether to rule that out, or, how you would need to work around it if it is contributing to increasing hardness.

 

[seangee]

If the linked stone is what is used that is indeed a problem. The dilution effect of mixing RO is linear - so your original mix of 1:3 should give you 268/4x3 = 201. Of course that is only for the new water. It will take several substantial water changes for you water to drop to that level. If you do go 2:2 and change 50% of your water it will only reduce the overall hardness by 25% which will not be an issue for the fish.

But if your stone is leaching calcium back into the tank it may be pointless

 

[Nemo2182]

If the linked stone is what is used that is indeed a problem. The dilution effect of mixing RO is linear - so your original mix of 1:3 should give you 268/4x3 = 201. Of course that is only for the new water. It will take several substantial water changes for you water to drop to that level. If you do go 2:2 and change 50% of your water it will only reduce the overall hardness by 25% which will not be an issue for the fish.

But if your stone is leaching calcium back into the tank it may be pointless

Well when I did the rescape i did the full fill @ that ratio. And changes the same every since...

 

[Byron]

Diluting hard water with RO is proportional. This assumes nothing in the tank is affecting the GH (which seems an issue here). But if that were not the case, then mixing RO and tap 50/50 would reduce the GH by half, and so forth. But the calcareous rock/stone will thwart this.

As for the fish, Corydoras habrosus need softer water, no question. Guppies can manage with 10 dGH (= 180 ppm) and would likely be OK a couple degrees lower. The cories should not be in water harder than around 8 dGH (140 ppm).

 

[Nemo2182]

Diluting hard water with RO is proportional. This assumes nothing in the tank is affecting the GH (which seems an issue here). But if that were not the case, then mixing RO and tap 50/50 would reduce the GH by half, and so forth. But the calcareous rock/stone will thwart this.

As for the fish, Corydoras habrosus need softer water, no question. Guppies can manage with 10 dGH (= 180 ppm) and would likely be OK a couple degrees lower. The cories should not be in water harder than around 8 dGH (140 ppm).

Yep I was trying to get around 200ppm to start with and then aim for 150ppm

 

[Nemo2182]

So quick update on the GH...By doing 2:2 ratio of RO:Tap I have managed to get ppm down to 196.9 which im alot happier with. Thats only after two 40% changes, so hopefully I will get a little more, but may have to start looking at 3:2 to get down to 150ppm mark. I measure my water straight out tap today and that was DKH 17 @ 304.3ppm!!! So that added with my calcuim rich rock is probably why I been struggling to get it down. Ive also for the first time got my Nitrate to 5ppm. So 0 A/ 0 Ni/ 5 Na, so happy tank