Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
If your tap water is OK, just too hard, then you do not need to buy anything to re-mineralize the RO. Use a blend of tap water and RO.
Test to see if you need RO system at all:
Put some tap water and some peat moss in a bucket. (Perhaps a quart of water and a 1/4 cup of peat moss). Stir whenever you think about it. Test every few days:
GH, KH, pH, TDS.
SOME peat moss seems to be pretty good at softening the water, and lowering the pH. If this works for you, then you will need to set up your water changes ahead of time, running a small pump in enough water with a bag of peat moss. (Nylon stocking makes a good bag: A knee hi of peat moss for 25-50 gallons of water, less for a smaller volume of water). The peat moss can be reused a few times, but test the result.
For our purposes there is no significant difference between RO and distilled water. You can buy some RO or distilled and run some tests with your tap water and all the aquarium tests you have. If the tests show that this is the answer, then look into buying your own unit. (see below)
I had a very complex system that really was overkill for my pretty decent water, but here is what I did:
System was a 2-part water treatment. The pre-treatment softened the water so well that I just used that for most tanks. For breeding Rams and keeping other very picky fish (Discus, Cardinals) I blended RO with the pre-treated water, then filtered it through peat moss.
I have several garbage cans (Rubbemaid Brute, on wheels).
The day before water changes in the most picky tanks I would half fill the 32 gallon Brute with RO, and half pre-treated water. I added a fountain pump set up to flume the water, and surrounded the intake of the pump with a nylon stocking (Knee-hi) of peat moss. The pump drew the water from the bottom of the can through the peat moss, then pumped it toward the top of the can. This is the best circulation method.
I added only dechlor to this can. I had an aquarium heater hanging in the can to keep the water warm. If it still was too cool, I would heat some of the water in a stainless steel pot on the stove and dump it back into the can.
For hard water tanks I used straight tap water (which was still fairly soft) and filled the can with that. Then I added baking soda for KH and Seachem Equilibrium for GH. Dechlor, but no peat moss. Circulate that overnight or less. Equilibrium is hard to dissolve. I used the water as soon as the Equilibrium was dissolved.
TESTS TO SEE IF RO WILL HELP
Buy a gallon of RO or distilled water.
Mix the following in separate containers of about 1 quart or more:
25% RO + 75% Tap water
75% RO + 25% Tap water
Test GH, KH and pH, and TDS if you have a meter (Get one, if you will be dealing with RO they are very helpful). Let them sit overnight, then test again.
Then add a handful of peat moss to the containers. Stir it around every few hours, and test the next day. GH, KH, TDS and pH. Then let these sit for a few days, stirring whenever you think about it, and test again.
Here is what you are looking for:
Which blend is best for the fish you want to keep? For the average soft water fish GH and KH well under 9 degrees, and under 5 degrees for the more picky fish is probably the goal. TDS in the low hundreds for average soft water fish, not much more than a hundred for the most picky soft water fish. Not all fish need the peat moss. This is a way of making 'Black Water'. Research the fish.
Is the mix stable? Does the TDS, GH, KH and pH stay the same (or pretty close) for the duration of the test?
OK, lets say you find that you need a 50/50 mix, and adding peat moss takes 24 hours to stabilize, then holds pretty good for a week.
You will want to buy a RO system that will produce enough gallons to make that 50/50 mix every week for a water change, and you will need a storage container where you can prep the water overnight.
BUYING YOUR OWN RO UNIT
If your water (well water) is very hard, or has certain minerals in it this will age the membrane in the RO unit very fast (and they are not cheap!). Look into some sort of pre-treatment that will at least exchange the worst minerals for something that is a bit more RO-friendly. You might need to talk with a local expert, perhaps someone who sells water filtration systems in your area. Perhaps get some professional tests done on your water to see what is really in it.
Then start pricing set ups:
Salt (if you go with a pre-treatment system)
Electricity if you need a pump (RO is very inefficient at low water pressure)
Waste water (can you use it in the garden?)
Then try to get an estimate of how many gallons the system will produce before you need to replace the parts.
Do some math. Is it cheaper to get your own system? Or is buying RO water locally the way to go? What does it cost to go to the store? (if you are already there for groceries etc this is not an issue, but what if you run our of RO water and have an aquarium emergency?)
You can buy lots of RO water ahead of time and store it. Set up a rotation so you are always using the oldest bottles. (This also counts as emergency water for your family if you cannot get water out of the well when the power is out.)
If your well water is so awful you need a pre-treatment system, then maybe you and your family ought not to be drinking it, and the cost can be shared between the needs of the family and the aquariums. If you are already buying bottled water for the family, but you get one of these systems you can stop buying bottled water.