Can I go 100% RO?

[JustinKScott]

I have a proven breeding pair which are laying pretty regularly. However, their eggs never hatch for me like their previous (out of state) keeper.

I talked to my LFS who told me several people have tried to breed discus; but their eggs never hatch.

I assume something's in our water... Which has me a bit nervous for my family. However, for the immediate term; I'd like to solve my discus problem. I do age/aerate my tap water before use.

My discus are in a 55G, fully cycled, BB tank, 85F. I have an RO unit that's capable of more than 60G per day. I feed Calif Frozen Black worms.

Can I do 25-75% water changes everyday with pure RO?
Will there be PH spikes?
Will the lack of TDS hurt the fish/slime coat?

[JustinKScott]

I've been looking around for the last several hours. Looks like I can go 100% if I add buffer. I seem to recall buying some discus buffer when I bought the RO unit. So I'll start prepping the water every night before WC.

I guess we'll see in a week or so if the next spawn works.

[lofty]

first thing is to find out the hardness of your water, then you can alter the water accordingly, you say they are a proven pair, then you say their eggs never hatch , even for the previous owner, maybe not a pair ?

[JustinKScott]

The pair were from out of state, they didn't have this problem there.

I'll dig out my TDS meter tomorrow and measure the tap water. But it read pretty low if memory serves. I have the two chemical hardness tests too; will they show us something TDS doesn't?

[lofty]

yes, they will show you the k.h. and g.h., this will give you the hardness of the water, if both are high then you will probably have to go with r.o.

[rcomeau]

I don't have experience with RO nor breeding but from what I have read on SD...

The typical reason for eggs failing to hatch is that the PH is too high for the eggs to be permiable long enough for the sperm to fertilize them.


I have an RO unit that's capable of more than 60G per day.
I believe that one of the reasons for using RO water is to lower the PH to enable the eggs to stay more permiable long enough for the sperm to fertilize them. Have you been using your RO unit? In any case, what has been the PH of the water each time there were eggs getting fertilized?


Can I do 25-75% water changes everyday...
That frequency is more than enough to accomplish the Discus preference for clean water. It keeps nitrates lower than what bacteria filtration accomplishes otherwise and likely has other benefits that are still a mystery to me. Any frequency is ok as long as the new water has a close temperature and PH to avoid stressing the fish.


Can I do 25-75% water changes everyday with pure RO?
RO units take out bad stuff as well as good stuff. The good stuff needs to be put back into the water. 'Pure RO' implies that the good stuff hasn't been put back in yet. I will leave it to experienced experts to be more specific than that.


I do age/aerate my tap water before use.
Tap water typically has disolved carbon dioxide in it. Disolved carbon dioxide is carbonic acid which causes the PH to be lower than without it. Aerating tap water causes the carbon dioxide in the water to disipate. For my water, that causes the PH to rise to 7 to match the PH in the aerated tank water. Breeders often target a PH that is lower than 7. The RO unit removes the chlorine and chloramine. I don't know if there is a reason to aerate once that is done.


Will there be PH spikes?
That is for you to manage. Beginners, like myself, are told to manage it by doing as little as possible to the water chemistry. That means don't use chemicals to try to directly change the PH. Instead, heat and aerate water to make it the same PH as the tank water before using it to change the water. That often results in a PH that is too high for breeding so RO water is used.

You should be targeting a PH in the tank that is lower than 7, it should stays there over time, and it shouldn't change because you use water that is conditioned to have the same PH each time. For example, the PH in the tank should not rise after water changes as a result of aerating in the tank for the first time. And/or, if you are using RO water, the PH should stay lower than 7 because you have been consistently using the RO water.


I assume something's in our water... Which has me a bit nervous for my family.
Municipal tap water is intentionally designed to be safe for your family by having chemicals (chlorine and chloramine) in it to kill bacteria. Aquariums need water that does not kill bacteria. (The bacteria in the aquarium needs to live in the tank to be able to convert ammonia waste to nitrite, more/other bacteria is needed to convert the nitrite to nitrate, and so on.) Your challenge is to go from family-safe water, to bacteria-safe water, and to egg-safe water.

[John_Nicholson]

I would start with using about 70% RO and 30% tab water. In most areas of the country that is a working formula. If you water is still to hard than add more RO, is it is very soft than add less.

-john

[JustinKScott]

My aged tap water is around ph 7.2.

I'll start with 30% Pure RO changes every other day, and I'll use the discus buffer I have to keep the conductivity around 110-150 us/mm. I'll learn what that means is TDS a I go.

I'll let you know how this goes...

[JustinKScott]

Ok, so this is still not working. A week ago they laid eggs again and again the eggs didn't survive. I've been doing so many 30%WC that it's hard to imagine there's any original tap water left in there.

I've been adding 'RO right' to maintain the TDS at 70ppm.

What else can I try?


The eggs are laid, they turn a translucent yellow/brown color. The parents fan the eggs for 2days, no wigglers, then the eggs are gone.

[nc0gnet0]

I posted this in another thread but it applies to you as well. Here is what I would do:

Next spawn pull the eggs right after they get laid and put them in a tank heated to 83 degrees with water around 35 tds. Also add some meth blue to this water. If you get a substantially higher hatch rate then you need to play with your breeding water more next time around. If the hatch rate remains the same then your male is either not making good runs, or has fertility issues.

This will literally save you months of screwing around with things trying this and that while leaving the eggs with the parents.

[afriend]

Justin, an RO unit strips the water of almost all minerals, and should give you a TDS reading near zero. Water PH is controlled by the mineral content (primarly carbonate hardness) in the water. Since pure RO water has little or no mineral content, the PH will be very unstable and will be subject to large changes when small amounts of minerals are introduced. Adding a PH buffer is one way to stabailize PH. However, many people acconplish the same thing by adding back a percentage of non RO water. This is what John Nicholson was stating above. Suggest you perform an experiment where you add 10%, 20%, 30%, 40%, to the RO water and each time measure the resulting PH. Be sure to use aged/aerated water. Then determine the amount necessary to fix the PH at the level you want. This method of fixing the PH does not depend on the purchase of a PH buffer. Carbonate hardness is measured with the use of your KH test kit. I would not recomment trying to maintain a KH of less than 40 ppm unless you are experienced as the PH becomes unstable at lower levels.

[nc0gnet0]

Justin, an RO unit strips the water of almost all minerals, and should give you a TDS reading near zero. Water PH is controlled by the mineral content (primarly carbonate hardness) in the water. Since pure RO water has little or no mineral content, the PH will be very unstable and will be subject to large changes when small amounts of minerals are introduced. Adding a PH buffer is one way to stabailize PH. However, many people acconplish the same thing by adding back a percentage of non RO water. This is what John Nicholson was stating above. Suggest you perform an experiment where you add 10%, 20%, 30%, 40%, to the RO water and each time measure the resulting PH. Be sure to use aged/aerated water.

A lot of this has to do with the performance and age of your RO membranes, but I agree with it to a point. The statement is very accurate if your using RODI water. I also add a bit of RO waste water back to my Ro water to give me the desired TDS I require. I never bother to age/aerate my RO water, the process involved of making the water itself pretty much strips the water of all dissolved C02 content. (not the membrane but the slow trickle of the RO water output. I rarely test for PH, rather after you learn your water you will find yourself mainly testing the water with your TDS meter.



I would not recomment trying to maintain a KH of less than 40 ppm unless you are experienced as the PH becomes unstable at lower levels

Depends, but this is the level I maintain all my breeding tanks at, and I have never had an issue. If I drop below 20, this is where things get tricky for me. But I spent considerable time learning my water and what is safe and what isn't. As far as what I recomended, the low TDS of 35 ppm was for eggs only, not the breeding pair (yet). The intent of doing what I suggested was to determine if this (eggs not hatching) was water related or fertility related.

Rick

[JustinKScott]

Thanks Rick; that sounds like a great idea. I will try it out when they lay again. It should be soon, they are usually on a pretty stable 2week cycle.

Justin