Ro Instead Of Tap Safe?

Hi,
So I have quite a few freshwater tanks running, and it's getting quite expensive to buy tap safe every few months, I recently purchased an RO unit for my nano reef and was wondering if I can use fresh RO water in place of tap safe and tap water?

Thanks,
Ethan

 

Yes, though you will have to remineralize it I believe. stella1979 can help you out

 

Yes, though you will have to remineralize it I believe. stella1979 can help you out

Ok, hopefully she sees the tag, is it ok to use in the sort term?

Ethan

 

I remineralize my RO/DI water with Seachem Equilibrium.

 

Agree with the above...in fact, some soft water fish (like licorice gouramies) NEED such very pure water to thrive. For everyone else, remineralize the water before using it.

 

HI Ethan Sorry for the delay. I've been busy, busy the last few days... so much so that I've been missing Fishlore!

Anyway, yes, I use RO water for freshwater tanks but it is not safe in its 'raw' form as it's been stripped of minerals fish need as well as buffers (KH) that maintain a stable pH. I use Seachem's Replenish to restore minerals, (though I'll be switching to Equilibrium when my Replenish runs out), and their Alkaline Buffer to restore KH. I'm very careful with measuring these products to make sure I'm providing the same water every time I do a change. If you want, I'll be happy to go into the long explanation a little later today. In the meantime, Seachem's website and forum are great for learning how to use these products.

 

I have high TDS in my source water so I use RO on some freshwater tanks .
I don't waste my money on buffers like the fish industry would like.
So many people say your fish should adapt to your tap in too many cases .????
So I just cut my tap with RO to get the values I want.
Doesn't cost more then operating my ro unit and I never run out of buffer...
My fish breed like champs for the most part so ?

 

If you're using RO water, generally I recommend to cut it with tap water to achieve your desired mineral content. The exception here is if your tap water contains a copious concentration of toxic compounds (e.g. ammonia, nitrite, nitrate).

If using Equilibrium with straight RO water, I would also recommend adding in baking soda (NaHCO3). 1.14 grams (approximately 1/4 teaspoon) will raise 10 gallons of water by 1 dKH. 2-3 dKH will ensure some buffering capacity as well as providing some sodium and chloride mineral content (which Equilibrium lacks) that are necessary for osmoregulation.

Strictly speaking, one does not need a KH above 0: bicarbonate (and carbonate) is not directly acquired by fish from the surrounding water for any biological processes. They do have bicarbonate in their blood (as a buffer) but their red blood cells are able to produce bicarbonate from carbon dioxide via the enzyme carbonic anhydrase (Roberts, 2012).

It's not uncommon for discus breeders to have minimal (even 0) KH as their water change regimen (50% every day) generally negates the need for significant buffering capacity. That being said, most of us don't change water with as frequent or voluminous a schedule, so a 2-3 dKH can be helpful.

 

HI all,
So the two main reasons I wanted to use it was the cost of tap safe and the fact my tap water was 350 TDS last time I checked!


Will it work if I mix in tap water with the RO water?

I'll also look into a buffer, I seem to remember my lfs had some but I'll take a look next time I'm down there

 

Okay.... so my tap DOES have extremely high nitrates and I have a fantail goldie who alone does not need any help raising nitrates. I should have mentioned my own situation and why I chose to use dosed RO instead of cutting it with my tap. I am certainly not the expert on water chemistry, so... I'm hoping that somebody here can help me with the KH thing.

When I first switched to RO, someone here that I trust implicitly explained that a KH under 4 will cause pH to be unstable... AND there is so much advice regarding a stable pH being more important than the correct pH, so what gives guys? Is pH fine with zero or a very low number for KH? Please enlighten me.

 

When I first switched to RO, someone here that I trust implicitly explained that a KH under 4 will cause to be unstable... AND there is so much advice regarding a stable pH being more important than the correct pH, so what gives guys? Is pH fine with zero or a very low number for KH? Please enlighten me.

It ultimately depends on the unique ecosystem of the tank in question: (1) some people change large volumes of water on a more frequent basis, limiting the need for the buffering capacity of KH; (2) some tanks are inherently stable with minimal changes in pH, decreasing the need for the buffering capacity of KH.

Increasing KH in a pH-stable tank with a low (or 0) KH is, in effect, providing a solution for a problem that doesn't exist. As for "KH needs to be over 4 or your pH will be unstable", I don't find that to be true. For example, Lucas and Southgate (2012, p. 68) indicates that 50 mg/l alkalinity (equivalent to ~2.8 KH) can provide acceptable buffering capacity in aquaculture.

Another example, closer to home, is that both Tom Barr (the developer of Estimative Index fert dosing) and Edward (the developer of PPS fert dosing) both endorse 0 KH.

That being said, 2-3 KH is fine: my tap water is 3-4 and I don't find any particular overriding need to increase or decrease it.

 

It ultimately depends on the unique ecosystem of the tank in question: (1) some people change large volumes of water on a more frequent basis, limiting the need for the buffering capacity of KH; (2) some tanks are inherently stable with minimal changes in pH, decreasing the need for the buffering capacity of KH.

Increasing KH in a pH-stable tank with a low (or 0) KH is, in effect, providing a solution for a problem that doesn't exist. As for "KH needs to be over 4 or your pH will be unstable", I don't find that to be true. For example, Lucas and Southgate (2012, p. 68) indicates that 50 mg/l alkalinity (equivalent to ~2.8 KH) can provide acceptable buffering capacity in aquaculture.

Another example, closer to home, is that both Tom Barr (the developer of Estimative Index fert dosing) and Edward (the developer of PPS fert dosing) both endorse 0 KH.

That being said, 2-3 KH is fine: my tap water is 3-4 and I don't find any particular overriding need to increase or decrease it.

Hi, so I haven't tested my tap water's kh, however I know ammonia Is fairly high.

The 20G is fairly stable, I once left it 6 weeks (had exams so it slipped my mind) without a water change and the peramiters were fine, there is quite a lot of bio filtration to I put it's stability down to that.

As for pH, it sits around 7.6 and doesn't fluctuate much from what I've seen, same for my tap water.

My unit should arrive today, so I'll play around with it when it does.

Ethan

Okay.... so my tap DOES have extremely high nitrates and I have a fantail goldie who alone does not need any help raising nitrates. I should have mentioned my own situation and why I chose to use dosed RO instead of cutting it with my tap. I am certainly not the expert on water chemistry, so... I'm hoping that somebody here can help me with the KH thing.

When I first switched to RO, someone here that I trust implicitly explained that a KH under 4 will cause pH to be unstable... AND there is so much advice regarding a stable pH being more important than the correct pH, so what gives guys? Is pH fine with zero or a very low number for KH? Please enlighten me.

I didn't realise that KH and PH were so closely linked , I though there was some link, but not much affect on each other.

 

So... I’ve been thinking on what I want to add to this post...
don’t want to disagree per se, but more to clarify on specifics...

yes, Barr often uses 0kh, however, often it’s in conjunction with a specialized buffering substrate... wouldn’t say he would advocate 0kh in a gravel substrate or something similar...
remineralizing content is based on sub and inhabitants, and needs to be assessed by the individual tank itself.

stella1979 usually a kH of 3 is the bare minimum, 4 is often better for stability

Esimm03 you can use the ro water straight while just topping off. However, when doing a water change with RO you would need to remineralize. Not sure what tap safe is and why it’s so expensive, most of us here in the US use Seachem prime, for 1 tank a bottle is cheap and should last a long time. Likely prime and tap would cost less then buying ro and salts for gH and kH.

 

remineralizing content is based on sub and inhabitants, and needs to be assessed by the individual tank itself.

I think people often zero in on KH as the only buffer present. It's important to note that carbonates are not the sole buffering compound: Avril et al. (2014) notes that in many freshwater water ecosystems (particularly softer and more acidic environments), non-carbonate buffers - such as phosphate - are more prominent than carbonates.

Here are a few posts from Tom Barr at various forums on low KH:

(OP with a 2.24 KH asks if KH should be raised): Leave the KH alone, add more GH. A good general rule unless you want to reduce the KH.........
.
(OP with 3 KH asks if this is acceptable): KH's from 1-4 are good.

(Poster notes that he buffers his 2 KH water with sodium carbonate): Don't bother, 1-2 KH works fine.

Here is Edward's (PPS) recommendation for the remineralisation of RO water: "Do I need to dose baking soda to increase KH [in RO water]? No. There is no need to worry about KH unless you have African Cichlid fish. Plants and fish don’t need and don’t care about KH. Less chemicals better."

This is one particular thread at aquaticplantcentral.com where Edward and others discuss KH: the general consensus is that if you have 0 KH water from RO, it's better to keep it that way.

yes, Barr often uses 0kh, however, often it’s in conjunction with a specialized buffering ... wouldn’t say he would advocate 0kh in a substrate or something similar...

I might be misinterpreting your post, but to clarify: when I've read of "buffering substrates", in most cases the buffering is not alkaline but acidic. That is to say, it's typically a soil-based substrate rich in humic acid and other organic substances that assist in lowering softness and pH for some fish or inverts that are accustomed to that sort of environment. 0 KH water would, in my view, be more helpful as less of the acidic buffering would be depleted by carbonates.

I've not read of Tom Barr or others who suggest that 0 (or low) KH is only acceptable with an alkaline buffering substrate (which in itself, I find, is quite uncommon).

Again, I might just be misinterpreting your post and I'm hardly the last word on what Tom Barr has ever thought or ever written.

I do agree with you that it's species dependent, but the proportion of aquarium fish (e.g. some African cichlids) that have a noted preference for a certain level of carbonate alkalinity is, overall, rather small and specialised. Again, my view is: "0 KH is fine, so is 4 KH. It doesn't matter so much." To me, at least, it's a relatively minor water parameter and I try not to devote too much headspace given that there are otherwise more significant parameters (e.g. GH).

Edit: My memory is most likely conflating Tom Barr and Edward (of PPS) claims around 0 KH (specifically 0 KH). Regardless, both seem to generally agree that very low/low is acceptable and the vast majority of fish/plants are very likely indifferent to it.

 

Minnowette Haha, yes, sort of misread, but more that I didn’t elaborate... (likely was in a hurry, sorry)

Yes, acidic substrates, but substrates that keep things steady, vs inert. Realistically speaking, take Ada and ro (plus gH target), take Ada and tap (again, Same gH) will end up with same parameters within 24 hrs... under 2, closer to 0 for kH... sub itself is the “buffer/remineralizer/RO unit”...
So, in many cases it’s more “why fight the substrate, parameters are consistent”.... now switch this to a low tech, gravel based substrate (or similar), different forces come into play.... then, add to that the lack of wc (frequency/amount both), and IMO kH/ph stability comes into play...
Not as much about the kH NUMBER, but the stability of the water

 

. Not sure what tap safe is and why it’s so expensive, most of us here in the US use Seachem prime, for 1 tank a bottle is cheap and should last a long time. Likely prime and tap would cost less then buying ro and salts for gH and kH.

Seachem Safe is even cheaper than Prime.

 

Cardeater OP is using a product called tap safe... not something I’m aware of here in the US. 100% yes though, Seachem safe way less expensive, yet harder to use on smaller tanks. Also not shelf stable once mixed