Using a DIY Python, set the water temperature, using a finger to judge the temperature, start the flow into the tank. Add enough Prime to treat the entire tank contents. Wait for the tank to fill, and shut off the Python.
There are many different tap water treatments that remove chlorine and chloramine. I personally use Seachem Prime with no problems.
If you are doing water changes with a "Python" type setup (i.e. water from tap is going directly into your tank), it is recommended that you put the Prime into your tank just before adding in the new tap water. Also, in this situation, it is recommended that you put enough Prime in your tank (I believe Prime is 1ml per 10G) to treat the entire tank, not just the new tap water. So, if you were swapping out 25G of water from a 50G tank, you would treat with 5mls, rather than just 2.5ml.
If, for some reason, you put your tap water into another container before moving it into your tank, you only need to use enough Prime to treat the new water.
not sure why you would add prime to treat an entire tank when you only removed say half the water. So if you had a 60gal and removed 30gals why redose 60gals worth of treatment? I use cheapo pond stuff i found at home depot costs 8 bucks. I stick a few caps during the refil. Its 10 or 20 gals per cap so i put enough to treat just the water being refilled since its diluting with the already ok water. I use a modified python, aka cut garden hose with hose connectors and mezzi style adapter hooked to my kitchen sink. Picked it up at the local fish store for 10 bucks. using pre filled 5 gallon bottles sucked! i did that for two years before i got smart.
I add prime or Amquel based on how much tap I add back.
I squirt and refill the tank back up.
Same temp(your hand is accurate to about +/- 1 degree F difference- pretty good really).
I'll add the ferts right after once the tank is full. Traces, KNO3, KH2PO4, GH booster. That's it.
You do this every day at 50%, you do not need to any other dosing and the system is extremely stable, but you cannot over do the water changes nor is it difficult to reset any dosing errors you might make by simply doing an extra water change or if there's a problem, do another water change, or a larger % say, 70% etc.
This resets the tank and rules out any nutrient related issue, because 70% or more of the tank is now just like a reference standard solution, that is the idea behind EI to begin with, 50% weekly seems like a lot of water to change unless you have high bioloads, but it really does not take long vs say 20% and we have clean and prune etc more often than that generally.
If you do daily 50-70% and dose back right after the water change, now after a week or so, you are going to be very very close the reference solution, no test kit needed.
So you can rule out any such errors with nutrients rather easily with water changes and dosing with dry powders or liquids. Light can be measured some what reasonably these days using a PAR meter, leaving only CO2 as the thorn in everyone's side.
Common aquarium care things like filter cleaning and other basics often get over looked at times also. But those can be addressed also.
The general idea it limit the amount of variables, rule things out and leave yourself with only a few things to monkey with. If you try and measure and test every darn thing, it's simply too much work, data to mull through, too hard to interpt.
Some think they have to do that. There are easier ways to get around it.
Some might hate water changes, so they are willing to do the calibrations and use the test kits and live with the assumptions. That's fine as well. I have great tap, so I use it and make and automate the water changes to remove the issues with changing water. You cannot automate the test however. I also have my arm in 24" or more of water if the tank is full, I like 1/2 the water gone so I can work and prune and tend the tank, this hobby is about aquatic horticulture, not set and never touch again.
You can do either, but generally it's better for most folks to get in and prune and clean with the tank 1/2 full, so while it drains and refills, that gives you about 10-60 minutes to clean inside depending on the fill rate etc.
I like doing my pruning before draining the tank, just to use the draining to get rid of more of the debris that is released into the water by pruning, pulling up some of the stem plant bottoms, replanting tops, general fluffing of the plants while doing this. My water tends to be rather messy after doing that.
I don't know why Seachem says to add Prime based on tank volume and not added water volume, but they do. I think the question was asked of them on one of the forums, and I think they gave a good reason, but this is a senior moment for me, so I don't know what they said.
KId, alos, using RO is nice in some respects because it does rule out most (not all, depends if you tend you RO unit and change the filters, particular the Carbon prefilter and keep that in good shape and test the out going water) variations, so when you dose there after, you know there's good consistencty.
This really is not that good of a trade off however in practical cases for perhaps 99% of folks. Some that have real hard KH's, like less for certain plants(maybe 10-20 species) or for certain fish. Then blending the RO with tap is generally what is done.
There are trade offs based on what goal/s you might have. So while in general, most do not need, or require RO in any way, in a few rare cases, or perhaps not so rare to those living in hard water areas that like to bred discus etc, there is a good reason to use it.
But if we know the goal, we know the tap water as well, then you can make a much more informed decision about which direction to go here.
And save yourself a lot of time and effort.
I help set up a 700 gallon tank and 1000 gpd RO unit for a client in LA. This way they can simply turn a valve to do a 50% water change, and the thing refills automatically. The whole house has a massive carbon filter so there's no chlorine etc. But you need the $, the room and all for that.
Always some trade off.
I have very soft water here, nasty just a few miles away, so I had to use a little RO and here I have to add more GH.
I rarely mess with the KH other than making it lower with RO in hard water taps.
-I am going to get my CO2 working properly. My current reactor is burping all of the CO2 at 1bpm. I am going for DIY.
-I am going to add a canister to make sure I have no dead spots and for the redundancy.
-I am going to transition back to tap water.
-Switch to dry ferts.