I am having trouble maintaining stable KH levels in my 40l marine tank and Ph is dropping also.

It has been set up for about 16months now and has been running well up until a few weeks ago.

The changes I have made recently are removed tomato clown and added camel back shrimp and a couple of months before I changed salt from red sea to marinium. I use RO/DI water for mixing salt

Current stocking is 1x glass shrimp 1x CamelBack shrimp, corals (mostly frags) a couple of medium sized pieces.

Filtration is mostly chemical, purigen, phosGuard, biochem-zorb.

I change 4.5L of water per week and dose Aqua Vitro Balance, calcium, fuel, twice weekly

I don't have test results with me but phosphates 0, nitrates 0 or very close to, dKH drops to 4.

Is there anything else I should be testing for?

Anything else I should be adding? not adding?

what corals and other inverts do you have some use calcium hence the need to top it up with supplements or other methods they may be the reason why

also other elements come into play when keeping KH and ph stable

you say filtration is mostly chemical

what do you use to filter the water, sump?

organic waste can affect your kh and this in turn will affect your ph

what corals and other inverts do you have

2 Shrimp, 1 Astrea Snail, trumpet, candycane, mini xenia, acro, kenya tree, zoas, hairy mushroom, Most are frags and still small. The trumpet started to die back overnight, one day was looking great the next I thought it was completely dead, That is when I noticed the Kh and PH was down.

you say filtration is mostly chemical

what do you use to filter the water, sump?

organic waste can affect your kh and this in turn will affect your ph

No Sump, overhead filter (aqua one tank) about 2.5 - 3kg coral rock in the tank, No Skimmer.

The tank seemed to be running better with smaller water changes and feeding more with the Tomato clown in there, so I assumed it would be fine with slightly larger water changes and less feeding, guess I was wrong. :dunno:

are you filtering your own top up water or buying bottled water

your system could do with a skimmer

and how often are you cleaning the top filter on the tank

not a great fan of using the top filters for marine i am afraid

you have a low bio load which is good

do you test for magnesium?

are you filtering your own top up water or buying bottled water

your system could do with a skimmer

and how often are you cleaning the top filter on the tank

not a great fan of using the top filters for marine i am afraid

you have a low bio load which is good

do you test for magnesium?

I use bottled water.

Yes I know I could use a skimmer and I plan to change my setup later this year to run a sump with a skimmer.

I don't have a magnesium test kit, I wondered if this could be low. I will see if I can borrow one.

do you have a pic of the tank?

Do you have a substrate or is it just a bare bottom?

You need something to drive the water on the bottom of the tank so mulm doesn't build up in the rock. Without a skimmer you NEED to be doing daily water changes.

If your planning on changing the set up later on in the year then I would sell the live stock and just keep cooking the rock. It is after all life we are talking about. Marine takes research and patience.

Don't think I have a pic on this PC, will try to remember to take a current pic tonight.

Do you have a substrate or is it just a bare bottom?

You need something to drive the water on the bottom of the tank so mulm doesn't build up in the rock. Without a skimmer you NEED to be doing daily water changes.

If your planning on changing the set up later on in the year then I would sell the live stock and just keep cooking the rock. It is after all life we are talking about. Marine takes research and patience.

tank has a substrate and plenty of flow to move mulm around and into the filter.

I have done a lot of research and have been quite patient adding any livestock slowly.

I realise that this setup will require more water changes than other tanks but I also have seen other tanks setup similar with less water changes and have been running longer than mine with no issues.

Found this pic from sometime last year

coraline has been growing on most places now, and not really many more corals

you may find organic waste in your substrate is affecting your kh, ph

would it be worth removing the substrate?

yes it would be worth it just to see if that is the problem

i have always been a fan of substrate but run with none now

if you have fauna that turn it over it is good

but without, it can be an organic waste trap

remember when you remove it you are changing the balance of bacteria in the tank

preheat some new salt mix for water changes afterwards

personally i would remove 1/2 the substrate then the other 1/2 a week later

Thanks LA, I have mixed some more salt last night so I can take out half substrate this weekend, hopefully this will get things back to normal in there.

don't just take out the top half of substrate as this is where your bacteria is mainly

you may just expose a slightly more anaerobic layer

may just be better on second thoughts to take it all out by syphoning

then do water changes over next week or so

keep an eye on your water parameters

Thats what I have done. Taken about a third out by siphon today with water change, I will continue over the next couple of weeks.

let us know how it goes, I'd be keen to see the results 8)