Remineralising RO water with waste water

[Calamardo Tentaculos]

After the incidences of fish deaths after each water change, I would like to completely avoid using my tap water.

Instead of adding tap water to remineralise the pure RO water, I've started adding back some of the waste water instead.

As far as I can tell, the waste water has no chlorine or chloramine since it goes through the sediment and two carbon chambers. I no longer need to use Prime or dechlorinator.

I need a lower proportion of water to achieve a TDS of 120. More interestingly, it results in a lower water pH of 6.5-7 instead of pH 7.5 when mixed with tap water.

Seems to be all positives. Am I missing anything?

 

[bazz]

Hi,
Sorry to hear of your fish deaths.
You might just want to add a small amount of Magnesium via Epsom Salts to try and achieve an approximate 3 - 1 Calcium - Magnesium ratio. It all looks pretty good to me.
Cheers!

 

[Bradders]

After the incidences of fish deaths after each water change, I would like to completely avoid using my tap water.

That is bizarre. I dont want to drag you through the whole sad event, but could you provide some details of the water change? i.e. change amount, water conditioner name and dosing amount etc? No tap water (treated) should kill fish.

 

[Calamardo Tentaculos]

Hi,
Sorry to hear of your fish deaths.
You might just want to add a small amount of Magnesium via Epsom Salts to try and achieve an approximate 3 - 1 Calcium - Magnesium ratio. It all looks pretty good to me.
Cheers!

Thanks! So is there a lack of Magnesium even in the waste water?

That is bizarre. I dont want to drag you through the whole sad event, but could you provide some details of the water change? i.e. change amount, water conditioner name and dosing amount etc? No tap water (treated) should kill fish.

You can see the details from my post history on this forum but the gist is that I had been losing pygmy cories steadily for a while. I noticed that most of the deaths occurred after I do a 50% water change. The fish were kept in a 27l tank; water was simply RO water mixed with tap water and Seamchem Prime added to dechlorinate. I targeted a TDS of 150 which resulted in water parameters of pH 7.5, 5 KH and 8GH.

Historically, I was constantly losing neocaridina shrimps over a period of time when I was using 100% tap water so I switched to RO mix. The neocaridina deaths stopped but I would have pygmy cory deaths after each water change unless I kept water changes to 10-25% of the tank volume. Recently, I lost the rest of my pygmies and a number of my neocaridinas after a water change so I am looking to avoid any unfiltered tap water to see whether there will be a different result.

I am in a new build estate development so my theory is that there might be something in our water pipes or storage tanks.

 

[Bradders]

Thanks! So is there a lack of Magnesium even in the waste water?


You can see the details from my post history on this forum but the gist is that I had been losing pygmy cories steadily for a while. I noticed that most of the deaths occurred after I do a 50% water change. The fish were kept in a 27l tank; water was simply RO water mixed with tap water and Seamchem Prime added to dechlorinate. I targeted a TDS of 150 which resulted in water parameters of pH 7.5, 5 KH and 8GH.

Historically, I was constantly losing neocaridina shrimps over a period of time when I was using 100% tap water so I switched to RO mix. The neocaridina deaths stopped but I would have pygmy cory deaths after each water change unless I kept water changes to 10-25% of the tank volume. Recently, I lost the rest of my pygmies and a number of my neocaridinas after a water change so I am looking to avoid any unfiltered tap water to see whether there will be a different result.

I am in a new build estate development so my theory is that there might be something in our water pipes or storage tanks.

That is horrendous. I am sorry to hear about that (and I think I recall your thread somewhere, sorry).

Have you tested your tap water for parameters? If your Ammonia, Nitrite, and Chlorine are sky-high, then I would (theorising) suspect that the Water Conditioner cannot address the chemicals. But it would have to be sky-high.

 

[Calamardo Tentaculos]

That is horrendous. I am sorry to hear about that (and I think I recall your thread somewhere, sorry).

Have you tested your tap water for parameters? If your Ammonia, Nitrite, and Chlorine are sky-high, then I would (theorising) suspect that the Water Conditioner cannot address the chemicals. But it would have to be sky-high.

I don't have a chlorine test on hand, but my test of the tap water did reveal presence of nitrates and nitrites. I am not quite sure whether tap water is supposed to have nitrites so I am giving this the benefit of doubt, but I am moving away from tap water to see whether it makes a difference.

 

[bazz]

Thanks! So is there a lack of Magnesium even in the waste water?

I think there is a general lack of Magnesium in tap water across most of the UK. If your aquarium is only 27l you would probably only need to add about half of a gram or so to your change water.

 

[Bradders]

I don't have a chlorine test on hand, but my test of the tap water did reveal presence of nitrates and nitrites. I am not quite sure whether tap water is supposed to have nitrites so I am giving this the benefit of doubt, but I am moving away from tap water to see whether it makes a difference.

They will usually. As an example, my tap water (Essex and Suffolk Water) has 16 PPM Nitrate, 0.07 PPM Nitrite. 0.15 PPM Ammonia and 0.85 PPM Chlorine/Chloramine. Water Conditioners should address 1-2 PPM of chlorine.

Anyway, I hope you get it all sorted. Such a pain that you cannot trust your tap water.

 

[G H Nelson]

Hi
How much Prime are you adding?
How are you adding it?

 

[tam]

If it's a 27l tank, I'd be tempted just to go with a gh/kh remineraliser - a pot is going to last you a pretty long time.

 

[MichaelJ]

I don't have a chlorine test on hand, but my test of the tap water did reveal presence of nitrates and nitrites. I am not quite sure whether tap water is supposed to have nitrites so I am giving this the benefit of doubt, but I am moving away from tap water to see whether it makes a difference.

If it's a 27l tank, I'd be tempted just to go with a gh/kh remineraliser - a pot is going to last you a pretty long time.

I agree.

@Calamardo Tentaculos . For such a small tank and small of amount WC water (13 L if you're doing 50% WC) I would just remineralize it to your targeted 8 dGH with 2 grams of CaSO4 (food-grade Gypsum salt) and 1.5 grams of MgSO4 (food-grade Epsom salt). This will yield approximately 36 ppm of Ca and 11 ppm of Mg for a total dGH of 7.65 in a 3.2:1 Ca:Mg ratio.

I doubt you need that much water hardness however - depending on other species you keep. Alternatively you can instead target a more moderate 5.5 dGH in a 3.5:1 ratio with 1.5 gram of CaSO4 and 1 gram of MgSO4.

Cheers,
Michael

 

[Calamardo Tentaculos]

Hi
How much Prime are you adding?
How are you adding it?

Used to be a bit more cavalier with the amount but nowadays I use a pipette to ensure that it is as accurate to the volume as possible.

I agree.

@Calamardo Tentaculos . For such a small tank and small of amount WC water (13 L if you're doing 50% WC) I would just remineralize it to your targeted 8 dGH with 2 grams of CaSO4 (food-grade Gypsum salt) and 1.5 grams of MgSO4 (food-grade Epsom salt). This will yield approximately 36 ppm of Ca and 11 ppm of Mg for a total dGH of 7.65 in a 3.2:1 Ca:Mg ratio.

I doubt you need that much water hardness however - depending on other species you keep. Alternatively you can instead target a more moderate 5.5 dGH in a 3.5:1 ratio with 1.5 gram of CaSO4 and 1 gram of MgSO4.

Cheers,
Michael

I decided to get a larger tank so now have a 27L, a 10L and a 54L tank. Water changes aren't that easy anymore hence why I am exploring the option of remineralising using waste water.

I'm not sure I have the appetite to purchase and measure out different ingredients. I rather pay more for an off-shelf remineraliser TBH.

Happy to switch to APT Sky or any other remineraliser if my proposed method is not feasible.

 

[MichaelJ]

Water changes aren't that easy anymore hence why I am exploring the option of remineralising using waste water.

Quick question: What is your current RO to Tap ratio to meet the targeted 8 dGH (120 ppm TDS) ?

Cheers,
Michael

 

[Calamardo Tentaculos]

@MichaelJ it was 150 TDS so tap to pure water ratio of 4:10. PH of 7.5.

Currently I'm aiming a TDS of 120 using waste to pure water at a ratio of approximately 2:10. PH of 6-6.5.

 

[MichaelJ]

I decided to get a larger tank so now have a 27L, a 10L and a 54L tank. Water changes aren't that easy anymore hence why I am exploring the option of remineralising using waste water.

I'm not sure I have the appetite to purchase and measure out different ingredients. I rather pay more for an off-shelf remineraliser TBH.

Happy to switch to APT Sky or any other remineraliser if my proposed method is not feasible.

If you suspected you had a Chlorine/Chloramine issue and the usage of Prime in the recommended dose didn't solve the problem, I suspect it might have been something else in your tap water or something entirely different that caused the issues with your livestock. Yes, the stages of RO are: Tap -> Sediment filtration -> Carbon filtration (which removes chlorine, pesticides etc.) -> Membrane (that removes most of the rest) -> pure water. But keep in mind that everything that the membrane would otherwise remove would be right there in the waste water - that could include Copper and other toxic metals like that which especially Shrimps are very sensitive to and possibly also the Pygmy's.

If you end up having to use 20% waste water in your 50% WC water consider this: Assuming you would change 50% in every tank weekly (10L + 27L + 54L) * 0.5 = ~45 Liters of pure RO water per week... instead of just 36 L if you would add 20% waste water... Is that 9 Liter per week difference really worth the consideration and worth having to deal with the unknowns of the content of that waste water, instead of just adding a bit of Calcium and Magnesium from blends you can purchase off the shelf to the pure RO water? If having to make the additional 9 liters of RO water is an insurmountable barrier, I'd recommend just doing 40% WC's instead of 50%...

Cheers,
Michael

 

[dw1305]

Hi all,

I am in a new build estate development so my theory is that there might be something in our water pipes or storage tanks.

I'd be really wary of chloramine in the water supply around <"new developments">.

cheers Darrel

 

[Calamardo Tentaculos]

If you suspected you had a Chlorine/Chloramine issue and the usage of Prime in the recommended dose didn't solve the problem, I suspect it might have been something else in your tap water or something entirely different that caused the issues with your livestock. Yes, the stages of RO are: Tap -> Sediment filtration -> Carbon filtration (which removes chlorine, pesticides etc.) -> Membrane (that removes most of the rest) -> pure water. But keep in mind that everything that the membrane would otherwise remove would be right there in the waste water - that could include Copper and other toxic metals like that which especially Shrimps are very sensitive to and possibly also the Pygmy's.

If you end up having to use 20% waste water in your 50% WC water consider this: Assuming you would change 50% in every tank weekly (10L + 27L + 54L) * 0.5 = ~45 Liters of pure RO water per week... instead of just 36 L if you would add 20% waste water... Is that 9 Liter per week difference really worth the consideration and worth having to deal with the unknowns of the content of that waste water, instead of just adding a bit of Calcium and Magnesium from blends you can purchase off the shelf to the pure RO water? If having to make the additional 9 liters of RO water is an insurmountable barrier, I'd recommend just doing 40% WC's instead of 50%...

Cheers,
Michael

Thanks! I knew there could be something off about using waste water, but erroneously assumed that all contaminants would be left in the filters.

So what else would I need to remineralise? Calcium and magnesium would be enough to increase both GH and KH?

 

[MichaelJ]

Thanks! I knew there could be something off about using waste water, but erroneously assumed that all contaminants would be left in the filters.

So what else would I need to remineralise? Calcium and magnesium would be enough to increase both GH and KH?

I assume you're not injecting CO2 ... if you want to keep your pH low you really don't want to increase the dKH/Alkalinity beyond perhaps 0.5 - 1 dKH. Add 0.5 gram to 1 gram of Potassium Carbonate (K2CO3) to your 45 L of RO water to increase the dKH to 0.45- 0.9. This will only increase your dKH.

Cheers,
Michael

 

[Calamardo Tentaculos]

@MichaelJ Actually I have started using CO2 so am I right in thinking that I will need some KH to prevent pH swings?

 

[MichaelJ]

@MichaelJ Actually I have started using CO2 so am I right in thinking that I will need some KH to prevent pH swings?

Yes, with CO2 you may want a bit more dKH to ensure more buffering capacity... I am not a CO2 user, but the customary ~1 pH drop during injection might become an issue with sensitive lifestock if your pH is already low - say you sit at 6 pH and it drops below 5 pH... Otherwise I wouldn't worry about it... aim for 1-2 dKH and you will be fine. Several very competent members around here with stocked tanks inject CO2 with essentially zero dKH, @Wookii is one I remember that does that.

Cheers,
Michael