maybe i'm not fully cycled yet, i don't know. but what i do know is that my ph has gone from 7.6 - 7.8 to 7.0 in about 2 weeks. ammonia is 0-0.25,nitrite is steady at 0,nitrate 5.0, any ideas??

Remember that pH is not static which many people think. PH will change all the time, it tends to drop at night, and raises during the day. It will change when you add fish, or remove fish. The biological process will also have an effect on your pH so just because your pH is different from two weeks ago, I really wouldn't worry about it. You may find that your pH from your tap is 7.5, in a fully established tank that is quite well-stocked, the pH may well be much much lower.

It isn't uncommon to get small ammonia spikes. How many fish have you got? How high does your mitrate get at the end of the week.

If you have a problem with your biological filter, or if you are not fully cycled then you will have nitrite readings

my nitrite has been 0 for 3-4 weeks now and nitrate hasn't risen above 5.0 in the same time,ammonia got to .25-.50 about 2-3 weeks ago and i did a 25% water change and brought it back to 0, at that time nitrates were 5.0,and haven't changed. it's a 75 gallon tank with an oscar about 7-8 inches long and a red shouldered severum of about 5 inches in the tank.

Exactly how long has the tank had been set up with the fish you have at the moment? Are you saying that the mitrate doesn't rise above 5.0 even at the end of a seven-day period? That surprises me, with the fish you have in the tank size you are using I would expect your mitrate to be much higher at the end of seven days. However, if you say your mitritehas been Zero for 3 to 4 weeks than your bacteria is obviously doing the job because if it wasn't you are maybe I would be way up. However, you shouldn't really be getting any ammonia reading at all in a fully cycled aquarium, unless of course you are inadvertently causing the problem. Maybe cleaning the filters out too much, this is one cause of small ammonia spikes.

I shouldn't worry about your pH, unless you are keeping fish that absolutely require a high pH, you're much better off with a pH that is low.

i was concerned because i thought oscars needed about 7.8 ph, i do rinse my filters about every weekend but only the carbon ones. tank has been set up with fish in it since early feb. i'm running two HOB'S emperor 400's, thats 400 gph x2, i rinse the carbon filters in tap water maybe once a week, if they are pretty gross, if not then rinse every 2 weeks. also been treating my water with prime whenever i vacuum and remove 5 gal. or so. thats been once a week so far. i also have ceramic rings for media.

btd71 wrote
carbon is supposed to be disposable at the end of its useful life.
i don't see the advantage of rinsing it. better replace it with some
fiber or pot scrubbies for bacteria host.

PAUL wrote:


X2! Pot scrubbies work GREAT! I recently removed 11 HOB's full of them! LOL

Correct me if I am wrong but...... Is it not a GOLDEN RULE.... on the site that you never wash out anything from a filter with TAP.... water. Only in a bucket of water from ur tank?

btd71 wrote:

yeah you are right jamie but for a carbon media, there is no need to
wash it either tank water or tap because it has useful life that need
replacement once you reach the end of it.

so i can just put green pot scrubbies in place of the carbon filters?

btd71 wrote:


Don't worry about the PH. oscars can cope with a wide range of PH. anything from 6 to 7.8 seams to be ok as far as i can tell from other members. i have sean members with a very wide range, the main concern is water change/maintenance work don't cause a sudden drop. slow rise and falls are fine. thats another reason to do small water changes.

As for the cycle I would say its partly damaged or lost. as you say above your ammonia started to rise and a water change was needed to bring it down. my advice would be watch the ammonia, if it starts to rise do a water change to keep it about 0.25. don't change so much water to drop it altogether. if your ammonia starts to rise, that shows your cycle is damaged for sure and you will need a small amount of ammonia to regain the cycle process.

don't worry to much, your ammonia shouldn't get out of control as you are not way overstocked. I'll guess the way you maintain your filter is what gave you the problem. wash your media in old tank water, as Jamie pointed out.

I wash my sponge media(mechanical media) in tap water but I always soak it in a bucket of conditioned water after to remove chloramine. I only dip my bio media in old tank water. but to be honest the bio media is always very clean. the sponge seams to catch the dirt before it reaches the bio. I also have a spare set of sponge so i can simply remove it and replace it and get the filter back up and running. I do all the washing after.

btd71 wrote:


Yes you can remove the carbon and replace it with plastic scrubbers. it will give you more media area for bacteria to grow. I would do it in small amounts as even carbon starts to harbour good bacteria and the carbon could be a large part of your bacteria at the moment. if you do have a cycle problem removing it altogether may loose your cycle.