Rainwater or tap water?

[lotusgirl81]

I have a small tank that holds around 30L (I think that's about 5.5g?) and set it up about a year ago as a shrimp tank. I cycled it without any problems and put about 15 red cherry shrimp in but haven't had any joy - they never bred and over the year gradually died one by one so that now I only have one left. I'm keen to have another go (maybe with a few very small fish this time too) but don't want to restock the tank if the same thing is going to happen.

I'm wondering if it might be because our tap water is very variable in it's parameters. The town where we live draws its water from a river which has very variable flow seasonally, and also runs high at times with water let out of a massive dam only a few kilometres upstream. At the moment the water out of the tap has a pH of about 7.2 and is very very soft - kH and gH are both very low. However, at times during the year the pH has been up around 8.5 (not sure about the hardness, I've only just started testing that).

I know the cycle is still good - I've tested ammonia/nitrites/nitrates regularly and never get readings above 0, and this week took my last poor RCS out for 24hrs and put some ammonia in to double check it. It dropped from 4ppm to 0 in about 12hrs, and my one remaining shrimp went back in and is happy at the moment.

I do have access to rainwater which we collect in a tank off our roof for the garden. We live in a small country town so pollutants aren't likely to be a problem. Would this be a better source of water than tap water given that the tap tends to fluctuate a lot? If so, should I still use a water conditioner just in case or does it not need one?

 

[Essjay]

The problem with rain water is that it is pure water with no minerals. In other words it is very soft and shrimps won't survive in very soft water. If you choose to use rain water you will need to add some minerals to the water, at the same dosage per litre at every water change.

In the past, have the shrimps died randomly or soon after a water change?



And 30 litres is slightly under 8 US gallons.

 

[NickAu]

The other problem is having a steady supply of rain water year round.

I use rain water because we do not have town water and have to rely on tank water, the only thing I add to the water is Easy Life Fluid Filter Media.

I have 3 tanks like this.

My Red Cherry shrimp breed so fast that even 4 Betta females cant keep them under control.

Zero fear

 

[lotusgirl81]

They died off gradually as far as I can tell, it didn't seem to be related to water changes. Never saw much evidence of moulting so I guess that could fit with a mineral deficiency? I think I'll try the rainwater and add minerals, might get more consistency that way. Any recommendations for products/brands/methods?

 

[Byron]

I would suggest it may be easier to use your tap water with mineral addition. The first thing is to ascertain the GH and KH of your tap water. These are not likely to vary over time, since the water is coming from the same source. The pH can vary due to various factors, but I doubt this was the problem here. It was more likely low mineral content.

There are preparations you can buy to add with each water change. Another easier/less expensive option is to use a calcium/magnesium base substrate, such as dolomite or aragonite sand. You really don't need to worry about too high a GH/pH with shrimp like you might with some fish.

Byron.

 

[Baccus]

Aside from adding aquarium salts and the like to adjust the pH and gH with every water change, or even using a relatively stable substrate that will gradually leech minerals into the water for the shrimp such as "shrimp soil" or ADA. You could try mineral balls that are especially designed for shrimp and contain essential minerals in them that the shrimp are able to eat and absorb. From memory such mineral balls last a few months depending on the actual pH and gH of the tank water they are put into along with the number used and the volume of the tank.
The other main factors with shrimp from the easy Red Cherry to tricky Sulawasi species of shrimp they all require relatively stable water paramters, some are more forgiving than others, but they also require a varied diet. True shrimp are basically scavangers and opportunistic feeders in the wild but in a tank situation where you are the sole provider of foods it needs to be a complete and varied diet including proteins and greens.
You didn't mention with the tank if you had any live plants with the shrimp or even timber or rocks. Many of the mosses are perfect for shrimp because they trap minute food particles and are habitat for beneficial bacteria that the shrimp will feed off. The shrimplets will also find refuge in the tangle of moss even if there are no predators in the tank they will feel safer and have readily available food. Timber can also be good because again it harbours bacteria and releases tannins into the water. Tannins while not always looking nice to us can have great health benefits for the aquatic animals we keep. Timber will also alter the pH over time as the wood decomposes. Cholla wood is especially considered good for shrimp as is Indian Almond Leaves.
With the shrimp you had did you ever see evidence of a "saddle" on the females (this is easily spotted with low grade cherry shrimp but not so easily with high grade solid coloured cherry shrimp), if not is it possible that the 15 where hand picked and by chance only females where selected? Females tend to have the best colour even in low grade cherry shrimp and beginners often only select the "prettiest" shrimp while ignoring the low grade less colourful and eye catching males.
One last thing to note when I once had a tank of only cherry shrimp for a selective breeding project I was doing I noticed the numbers gradually decreasing. It had me stumped for a while until I saw the culprits that where decimating my shrimp, dragonfly nymphs. I had to strip the tank to get rid of the dragonfly nymphs and since then have always kept a semi predatory species of fish with my shrimp to take care of any undesired aquatic intruders. So far I have found Pacific Blue Eyes and Spotted Blue Eyes to be the most shrimp safe species along with corydoras catfish.

 

[StevenF]

could you list your GH and KH numbers you have now? There are two things you can do to maintain a stable GH. A GH booster would allow you to add GH as needed to keep th eGH stable.

A good one to try and Sachem Equilibrium. It supplies Calcium and magnesium, potassium, sulfur, and iron. Plants need all of these to grow.

Also you can add Dolomite to your tank. When the PH gets a little low it will dissolve releasing calcium and Magnesium. In the process it will push the PH up to 7 and at that point it should stop dissolving. It is like a heater thermostat and only turns on as needed. 1/8 cup in a 5 gallon should last years. This is solid GH booster.

You might also want to talk to your water utility. In addition to the regular water quality report they may be able to provide data on how the GH and PH changes over time.