Water hardness question

I went to look at a RO unit today and was told the following by one of the guys at the store and it doesn't make sense to me, none. He asked me what I needed a RO unit for and I told him that I wanted to drop my TDS to make my water softer and lower the ph for my eggs that keeps on dying. I said that I want to mix tap water and RO to get to a range of between 50-100 TDS and that will lower my GH and KH as well resulting in a lower ph.

I was then told that this would never work and that if you take say a liter of water with a TDS of 500ppm and mix it with RO water regardless if its 10 liter or a swimming pool size volume the end result in both will be 500ppm TDS. He also said that the ph will stay unchanged. He further told me that I must, MUST use discus buffer to drop the ph afterwards otherwise my fish will die pretty soon if I continue to use tap or tap/RO water and that's the only way to do it and that all the discus keepers does otherwise the fish will die. I tried to explain that this isn't correct and doesn't make sense but he was so adamant that I just left it and nodded awkwardly.

Now, this can't be correct or am I missing something or everything for that matter? Can someone with water managing experience please tell me if this is correct or not, it doesn't make sense to me.

I've got it like this, RO = almost 0 tds, 0 gh and kh, you ad tap water or RO waste to get your values to where you want it, the ph will follow after aging for the mix and will settle.

@Marco just tagged you in so you can see and maybe help clarify if I'm missing something.

 

RO should lower the tds heavily afaik.

I have very soft water already, although some places here in CT have hard water. My tap PH is very high but it's the co2 in the water, the PH quickly goes down below 8

 

I had a chat with marco and in he advises to mix RO with tap water to lower the tds


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@Adhil and @Hendre yes that's how i also have it, I don't know what the guy was trying to say as none of it made sense to me especially the part about the 500ppm and water volume. With water that has a low tds reading the ph in the tank will drop by itself over time and settle according to the low kh reading. Low kh = lower ph as there is less minerals to buffer the water with while the bio does it's work. I'm going to go buy the RO unit tomorrow and start mixing my water. Going to start with 30RO/50tap and test to see what the parameters are doing and take it from there.

 

Hi

@BoelderBeestie - it is very frustrating when shopkeepers or their assistants/staff hand out incorrect information like this. One would think they would be less ignorant, seeing that they are the ones needing to offer advice.
Anyway...
You are of course correct - if tap water has a tds of 100ppm, and your RO has a TDs of for instance 5ppm-then a 50/50 mix will result in approx 53ppm.

It will not however affect ph over short term, but the now lower tds will be of no buffering, and this will result in ph dropping over time

I will then also say that if you start using discus buffers and other snake-oils, then your fish will eventually die. If not used properly these things do more harm than good.

As far as ph is concerned
Effectively RO water has no ph. It is neutral 7
Adding any tap water will adjust the ph to that of the tap water. Short term.
Again as said - no buffering capacity now exist, and so ph will fall over time as hydrogen ion content rise in the water columb due to the nitrogen cycle being "acidic"

Dont get fixated on these things
For keeping discus a tds of anywhere in the region of 100ppm is perfect. Dont mess with ph unless its above 8

For breeding get the tds in the 50-70ppm range.
In that range a good hatch rate should be achieved, as long as healthy milt is produced by the male.

I hope this answers your questions

Rgds

Marco


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@Marco thanks for the reply, yes that's how I've got it too. Will pick his brain a bit tomorrow when I go get the RO unit. The only fish that's going to get the RO mix is my breeding pair. They where starting to have success the last couple of months and fertilizing the eggs properly but they die a day before hatching. This never happened before, the eggs that where fertile always hatched. I can see their development. I think our low dam levels here are making the water to hard for the eggs to osmoregulate properly. I've lost 3 spawns to this now.

 

@Reedfish I don't think I need to do that luckly. I just want to soften the water a little.

 

Hi

@Reedfish,
When referring to tap water I am referring to prepared tap water. That would be water that ideally has passed activated carbon, and then also had a dosage of some dechlorinator
AC would remove toxins and chlorine, chloramine would need dechlorination.
I dont really see the need for pure RO and salts. Well - not yet at least.

@BoelderBeestie
Somewhere in all this I am getting lost. I dont quite understand your post.

Eggs can not be fertilized properly and then die due to hardness. This is not possible. If the water is too hard (too high in Calcium Carbonate - Kh) then the eggs will not be fertilized.
Simple as that.
In other words what I am trying to say is that water can not be soft enough for fertilization but too hard for development/hatching.
This is simply not possible in egg physiology.
What I also dont quite get is that you see the eggs develop but on the last day they die? How do you see this, as egg development is only visible in the last 24hrs of development. Up until then very little changes

Osmoregulation in eggs is another contentious issue. I have done a great deal of research on fish eggs when I was raising Discus parasite free. I am now of the opinion that although osmoregulation is probably happening, it happens at such a slow rate that it is impossible to measure. Certain salinity tests that were done on eggs from various freshwater species substantiate this opinion.

So - in summary
If the Discus eggs are infertile or low in fertility, this is due to poor milt condition, either in production or distribution,
OR
incorrect water parameters AT TIME OF SPAWNING.
You need to get to a level of water hardness lower than 2°dh on Kh.
If not this problem will persist

Hope this helps

Rgds

Marco


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no need to use RO in Cape Town area for breeding discus or any other soft water loving fish
Our water is already so soft that buffering is required to prevent PH crashes due to the low calcium/magnesium content
speak to @pHish_man, he wil point you in the right direction

 

@Marco Here's what happens. They spawn and the next day the unfertilized eggs start to die off, they are still young so the are not getting good fertility rates to begin with. They started spawning last year November like clock work every 10 days or so and with each spawn they where getting better and better and more eggs started hatching each time. A month ago this just stopped and the 3 spawns they had since, the eggs that turn dark die the day before they should hatch.

The last spawn of the 3 there was only 11 eggs that turned dark and they died the same. The unfertilized eggs die within 24 hours, some a little later but they never turn dark. My tap water started to have a soil smell like a nursery and my aging barrel smells like a cycled tank now. My tap water never smelled like anything and if it did it was a light chlorine smell. My kh is 6 and my gh is 6-7 last night when I tested. I never had this issue, it started a month ago, they where doing great. Better with each spawn. I even had fry and I have one that hatched on the 1st that I'm raising.

They spawned yesterday again and this morning about 10% of the eggs are dead, I will keep an hawks eye on them and document whats happening. My reasoning for getting the RO unit was to soften the water and clean it up a bit as I though the hardness could be the trouble maker as it's quite high now. I don't remember what my tests where before I had these problems but it never bothered me, this kh of 6 is standing out like a sore thumb though.

My plan is to use the RO water and knock off the kh little by little till I start seeing hatches again, then I will know where my fish's limits are if this even sorts out the problem. I don't know what else to do. After reading your statement on that the eggs shouldn't die after fertilization and hardness isn't the problem is not good news as now I don't have a clue what could be wrong. Nothing has changed husbandry wise, I'm doing everything the same as always.

@mattie everything was going great till a month ago. I even have a baby I'm raising that hatched on the 1st. I was so glad that I didn't have to fiddle with my water and my fish was getting better and better at spawning but now nothing. The RO unit was my first plan to try and get to the bottom of this but now I don't know what could be wrong. In the past I had to buffer my oscar tank as my ph went way down. With the buffer the tank held at a ph 6.5 6.8 without the buffer it was at 4-5. Now its just over 7. Something is not right or I should rather say it's not the same as it always was.

 

Hi

@Reedfish
Those RO- salts are usually very consistent from what I have read.
Our water in SA is generally not too bad, although of late is has definitly deteriorated.
There are other options besides going RO and remineralising though. But thats a whole other discussion.

@BoelderBeestie
Can we get some sort of standard lingo going here to avoid confusion please?
Lets talk of eggs as eggs
"Dead eggs" or infertile eggs as White eggs
Developing eggs should be almost black in colour
Wrigglers are hatched eggs
Fry are free swimming fishies

Now - once eggs are spawned a small opening exist through which male milt should enter and fertilize the egg.
Soft water fish have very soft shelled eggs, and in the presence of high levels of Calcium, the eggs then water harden faster than what the male can fertilize them. Effectively the small entrance is closed because of it hardening in seconds.
U may have a very very small % that will hatch, due to plain luck - but the majority will turn white (die) in the proceeding 48hrs.

In soft water this delay in water hardening means the male has more time to deposit his milt on to the eggs, and then a higher % of the eggs are fertile.

You have had hatches so this means the male is fertile. This leaves us with water conditions.

This medium is not ideal for trying to convey the conclusions
But i will try

A Kh of 6dh is too hard. Its not even negotiable. You need to get that lower than 2dh. Then u will have high % fertility.
I breed my Rams in 90% RO water with a tds of below 20ppm. I have hatch rates of higher than 95% of eggs spawned.
This drops drastically as tds (kh) increases

Once an egg is spawned in soft water it takes approx 4 to 6hrs to water harden. Once the egg shell is hardened it is now an osmoregulating membrane.
Studies have shown that osmoregulation in freshwater fish eggs is a very slow process, if at all a process. But nevertheless - it still means it is effectively an RO-membrane
Now consider what that means-
It means whatever is inside stays inside, whatever is outside stays outside - and all that can pass this mebrane is pure distilled water.
What this means is that no matter what happens to the external environment of the egg, the internal environment stays intact and balanced.

Unless of course chemical damage is done to this membrane
I have however used chlorine and potassium permangenate as sterilizing agents and have had no ill-effect on egg development.

I am of the opinion that from what you are writing that there are a few minor mistakes here
Firstly i dont think the eggs are developing and then dying. If so you have a serious problem to which i have no solution. You would need to then figure out which chemical toxin is destroying the eggs. I do believe this unlikely as the most likely scenario is that the eggs are not truly developing.
I would need to see a photo of the eggs to determine.

Dont mess around with trying to find a balance. Just lower the tds of the water to a level of approx 60ppm.
Then let them spawn and see what % hatch. If still not hatching then have the water tested
I doubt the Kh of your water is 6dh. Thats higher than what we have here in PTa and we dont have great water.

Do not remove eggs. Leave them with the parents and see what they do. Raising Discus artificially is not rocket science, but in many cases I have witnessed that the fish are stunted and die a slow death at abt the 3mth mark. It is not easy to raise proper fish from artificial raising. It took me many many attempts to get it right and raise fish that grew to 16cm

So to summarize
Get tds to a level of approx 60ppm using RO water as a means to dilute.
Let the pair spawn and record fertility
If still low have the water tested and get an accurate measurement of Kh of the 60ppm water for future reference
Leave eggs with parents
If they hatch - congratz and now raise them

Kind regards

Marco





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Will do @Marco. Yes by dead eggs I mean white. What you've said makes sense. Maybe the darkning of the eggs I'm seeing is them just rotting from the inside. Will take pics as the eggs are progressing with the latest spawn so you can see whats going on.

I'm testing with test strips and they are known to be inaccurate, my next buy will be a tds meter.

 

@Marco... awesome article even for those who are not breeding discus... thank you..

 

Yes thanks @Marco I like how you explain things, easy to understand and very informative.

 

Yes kids, there you have all the reasons why I don't try to breed Discus. On a serious note though very interesting discussion. I learned a few thing here today. @BoelderBeestie when you collect your RO unit as the sales guy if he wants to share a coke with you, but mention you diluted it 50% with soda water. Should still taste the same?

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@Pierré Schoonraad haha. I got the unit, flushed it and I'm busy making 10L now to play around with. Not going to use it yet as we have heavy water restrictions here, will wait till the dams look a bit beter.

I see the kh reading on the tetra strips are not working. No matter what I do it stays at 6. The gh seems to work fine. Will go get a liquid test kit tomorrow to test with and a tds meter on Friday from spraytech.

 

Tested my tap and tank with a liquid test kit and got very different results from what the strips told me. Tap kh at 2 and tank kh at 1 so my tap water is perfect after all hahahaaa, feeling like a real poepol today.

@Marco your verdict was spot on all the eggs from the last spawn turned white. The "development" I was seeing was how the light falls on the eggs, just before they turn white the shadow that they cast makes them appear darker, it looks exactly like a fertile egg. The problem...my male is shooting blanks.

Its not a total loss as my crs tank is way off. No wonder they are dying. I can use the RO for them instead and it only being a 20L I won't have to waste water. I can use the waste on my guppies.