How long to hold onto homemade saltwater

[mark165t]

I have been making my own RO saltwater for water changes, how long can I hold onto and add to the bucket of saltwater that I did not use? In just the last few weeks I have seen my nitrate level too high and even after a 15 gal water change on a 75 gal tank i'm not seeing a drop. I am cutting back on feeding, 2 times with flake/pellets, 1 time with some of a portion of a cube of frozen marine cuisine daily.
My tank is now 5 months old, 12 fish, 1 cleaner shrimp, 4 hermit crabs, 2 snails.
Thanks
Mark

 

[tthemadd1]

Any live rock in the tank? Also that is a lot of fish depending on the size of each fish.
What type of nitrate test?
What type of filtration? Some fish are cows and some not even close in regards to waste.
I mix about fifteen to twenty gallons of salt a month. Keep it in a 35 gallon trash can (plastic) on my back porch. It has a pump pointed at the top of the water to keep it circulating. It is usually good for a month maybe longer. The risk is bacteria growing in the top off water. As long as you circulate it cpnstantly it should be fine.

 

[tthemadd1]

No direct sunlight and put a fabric cover to allow oxygen but not bugs dust etc to get into the water.

 

[mark165t]

I have a live rock/sponge in my sump tank along with some other tiny critters that live under it. I got that from a reputable dealer in my area.
My fish are all pretty small, the biggest one is my yellow stripe chromis. he has list his stripe and has been the fastest growing of all my fish.
I had been using an automatic feeder for several months, 2 times a day plus some frozen marine cusine in the evening. I just cut off the auto feeder and give a pinch of flake in the morning and still the frozen in the evening.
I just did a water change last weekend, 15gals on a 75 gal tank. I usually see a drop after that but this time I saw a spike up. I'm getting ready to do another 10gal change to see what change I get.
I have just recently started to change the filter sock at each water change. I have 4 of them and rinse them well and wash in bleach water. I will be just starting the rotation this week.

 

[tthemadd1]

Remember your filtration is populated with bacteria that help the nitrate cycle so alternate any filter cleaning. Don't pull hem all at once or you will kill off a larger population than you need to remove the waste from the water.
Do a big water change and then look at the readings. If they drop you need more surface area for waste removal else wise.

 

[tthemadd1]

Sorry that didnt make sense. If the numbers drop with a larger water change you need more surface area for bacteria.

 

[michaelkelley]

If the level is not dropping after changing the water, then I think the most effective thing would be to filter the water and check. I am not sure about the othe things, but this may help.