How do you fill such large tanks ?


New member
Lets say you have a 1000 gallon tank. How would you fill it ?
Do you find a very large RO unit or get snaller RO units to fill the tank at once.

Or use a single RO unit and wait a couple days ?

Thanks !

Reefer Brian

In Memoriam
Depends on how much time you have...

If you plan on having a 1000g tank I would suggest buying a commercial RO/DI unit for the demand needs(250gpd minimum).


Premium Member
You just buy a good RO/ID system. You only need one system. You are only going to fill up a 1000 gallon tank once. So you don't necessarily need a set-up that will put out 1000 gallons in a hurry. After the initial filling, you will be doing something like 100 gallon/week water changes. You will also want some water storage tanks for a system this big. I'd say at least one 100 gallon tank. It would be best to have about 300 gallons or more worth of water storage just in case you have an emergency that requires a large water change.

Buy whatever you can afford... of course a unit that is rated 180 gallons/day will put out twice as much as 90 gln/day unit. Basically it will take about 10 days to fill the tank with the 90 gln/day or 5 days for the 180 gln/dy unit.

You would definitely fill the tank with water first, then slowly add salt.


New member


I filled my 400 gallons about 75 gallons every second day. Made ro on one day, mixed the salt for 24, then added it to the tank. Rally helps you aquascape slowly going up a foot every 2 days.:lmao:


New member
My RO/DI produces 150gpd and I have a 200gal vat for mixing my salt water. I took me close to a week to fill my 700gal system.


Tangaroa to 500 gallons
Premium Member
...and if you're upgrading from smaller tanks, just pump the "old" water into the "new" tank to supplement the ASW you are making every day. I borrowed barrels from our local club to mix saltwater while continuing to make RO/DI in my Brute containers... a 24/7 assembly line until the work is done...



New member
I would size your RO/DI output (i.e., gpd) to no less than the amount of water you will need for a water change.


New member
i took about 10 days to fill my 1350gl....


part time superhero
It took me about 4-5 days to fill my 500g system. Although its a painful wait, I used the time to finish loose ends, etc.