[lindsay]

I like to do a good 5% to 10% water change each week on our coral systems but there are a lot of guys who don't do any water changes weekly at all .
Is this because nitrates ,phosphates are so low that there is no need ?.
Is it because it may upset the bacteria balance of the tank over a long period of time doing weekly water changes ?

[ben]

from what i can see a lot of the experianced reefers are doing less water changes because their filtration is very good and also it upsets the chemical balances,i.e calcium , kh ect.

[bobba fett]

I am with you Lindsay, I do 1bout 10% per week.

Having said that I have been adding sodium bicarbonate to raise DKH and epsom salts to raise Magnesium resently as both were low.

I am now wondering if this is due to levels being too low in my salt H2Ocean or whether they are being depleted quickly. I was just considering leaving the change for a couple of weeks to see what effect if any that has.

I am not using a skimmer on my system though so I feel the changes are needed to export nutrients

[chriss]

Just being cynical, but, how many just get lazy or want to save some money, of course, few would admit it. Do water changes get less frequent the closer to the bottom of the bucket you get?

Chris

[Dave.I]

On my last system water changes had to be done to keep everything in check but now in my new system with better nutrient export via a dsb bucket,carbon dosing and gfo i get a constant 0 for nitrates and phosphates even with heavy feeding.Im starting to wonder if water changes are needed as i will soon be running the balling meathod plus all the trace eliments.I just cant quite get my head around not doing water changes just yet!
Normaly i would do 15/20% every week or two.

Dave

[Social D]

Lazy here no idea why it only takes a few minutes to do a water change, The problem i have is i always say i'll do it next week it looks fine

Accoding to my bucket ive changed about 160g in a year on a 200g system not sure what percent that is a week lol

[dave14]

I do 5% weekly, but have been thinking about not doing it for a few weeks as nitrates and phosphates have been 0 for some time now.

If Tims tank is anything to go by we should follow his example lol

[Kevang]

I change about 10% every 2 ish weeks depending if it is raining or not (sump outside in lean to)

I would prefer to do smaller and more often but find it to difficult (lazy) and prefer keeping dry (cornwall)

The reason would be to keep topping up the essential nutrients that are in the salt and not in a bottle.



Will you really upset the balance of the tank by doing a water change?

If you have prep'd the water properly then surely not ie temp(ish), sg, mag, calc and Kh.

I haven't worried to much about temperature until recently as in the wild there can be quite marked changes in this as the currents change.

It doesn't seem to have upset the corals as they go mad polyping when the new water goes in.

cheers

Kev

[norman]

hello all, i change 10% weekly, check ph afterwards as tap water has lower ph than required. occasionally have to adjust with salifert ph&kh up. cheers, norman.

[Simon Garratt]

Here's my take on the situation.

Personnaly i think the need or justification for doing water changes varies dependent on the system.

I will say now that in my opinion, the first rule of thumb that overides all other considerations is your nutrient pool. If you have one that sits over NSW levels, then you should be doing water changes..no excuses.... as a means of diluting that exess. Thats origionaly where the old saying came from...'The answer to pollution is dilution' I do get a bit frustrated when i hear about no3 not being an issue etc and that fish and corals can adapt...There is a big diffeence between adaptation and tolerance. One is a long term change in biology over generations to keep an animal at an optimum level of balance with its surroundings (not to be confused with evolution), the other is a safety margin of 'over adaption' that allows the animal some survival leeway in the event of short term minor environmental changes or swings.

If your system does run low levels of nutrients with minimal effort, then you could look on water changes as a general refresher once in a while. There is no doubt that in many cases where tanks have been run for 5 yrs plus without water changes, then these systems have shown a sudden increase in coral growth, colouration and vibrancy. As to the reasons why, then that still needs more investigation imo, it may be a single thing, or a multitude of factorsall working together..

If your nutrient pool is in check, then you could consider minimising water changes to smaller amounts. but you also have to factor in two other areas. 1 is the gradual depletion of minor elements which can cause a gradual reduction in coral health over time and overal system quality (remember alot of elements are interlinked in salt water). the other is accumulation of toxins etc. ie those given out by many of the soft corals, anti-fouling toxins released by macro and micro algae as a defence against bacterial and microbial infesation, or simply the gradual release of toxins or contaminants from items that come into contact with the tank water (non food grade plastics etc), you could even factor in airborn contamination from houshold sprays, air fresheners, cooking fumes, smoke etc etc...the list is pretty much endless and non of it can be tested for, although admitedly with the use of carbon and possibly 03 much of this is removed or broken down but possibly not all. and finally you have a route that very few people think of as a contaminant pathway and that is top up. I'm fairly lucky in this respect that i run top up direct from the RO unit via solenoids, rather than through an exposed top up tank. remember that RO is very good at soaking up airborn contaminants whilst it is sat there doing nothing.

My system evaporates nearly 5 gallons a day, so thats nearly 2400 gallons of top up in just 16 months (24 x what ive done in water changes at around 100 gallons over that period) so its worth considering just how good your top up water is and testing the TDS if its sat in a holding tank for any period of time before making its way into the system. Its quite possible that you are adding more cr*p than you think you are, especially over the long term.

With regards to the depletion of minor elements then this is a difficult area imo. You can by way of a reactor take care of most of these, as long as you are using a decent media. personnaly i prefere coral branch media as it puts back into solution all the elements that were origionally bound (or nearly all), which is a bit more encompassing than many of the artificial or highly refined medias that are around that only fullfil part of the requirements. Strangely i was testing Sr the other day and found that within the realms of test kit accuracy, the reactor was kicking out 'slightly' more than the tank level, so this seems to answer one question thats been raised with regards to Sr supplimentation. As far as im concerned, if you are using branch media combined with regular water changes, then chances are you wont actually need to dose this element.

So all in all its pretty much a mine field of ifs and but's, and no two systems are alike in this respect, so its down to the keeper to test for overal system stability and then look at how the livestock is handeling things over the long term to deturmine whether a water change will help freshen things up and balance out those things that cant be tested for, be they depletions or accumulations.

As for water changes 'upsetting' corals. Personnaly i dont see why it should. If you are using the same salt brand consistantly, mixing properly and making sure that the water you are adding is at the same temp and pH as the existing water, then it shouldnt be an issue. I think alot of the time...this upsetting corals thing, is derived from doing water changes on systems where there are large differences in 'quality' between the tank water and water change water...If you are running the system good to start with with low nutrient levels and low turbidity, then the differences are far less impacting. Think of it this way. if you are changing 25% of your water for nice new clear water, and your existing water is slightly yellow, then you have an increase in photo transference as well. Its quite possible that the chemistry has little if anything to do with why the corals have shrunk back on themselves. Also its worth considering whether a bit of sliming is actually a bad thing. It can actually help a coral rid itself of pathogens or accumulations of dirt etc.

A common argument in the water change conversations is differences between the tank water and the water change water. To put it into perspective. If you have a Ca concentration in your tank of 450ppm and your water change water has a concentration of 410ppm, even if you were to change 50%, then you would only see a change of 20ppm ie a drop from 450ppm, to 430ppm. thats actually far less than recommended maximum daily shifts in this perameter. If you were doing a 25% change then you are only looking at a 10ppm shift in the tanks level from 450ppm to 440ppm. the same applies to other elements as well. The actual ratio of change in perameters on the entire volume, is often far less than the difference between the tank and the water change volume.

Regards

Simon.

[karnivor]

Thanks Si, an interesting post.
Ill just add by saying that I always tell people who have top up tanks that are not dosed with Kalk, to keep some Coral Gravel in the bottom of the tank. This will quickly but lightly buffer up the RO water so that it finds it much more difficult to pick up contaminents.

[lindsay]

The water change question is one that comes up regularly ,both on forums and in the shop .Ime sure the above posts will help people decide if they should or can get away without doing water changes .

[Simon Garratt]

To be honest Linds, I dont think there is a case of simply 'not' doing water changes. The laws of biology and closed system chemistry pretty much ensure that a closed system with growing corals and other life simply cant run a 'no' water change regime indeffinately. I think its more a case of working out how much you need to do and how often, whilst simply accepting the fact that at some point or other it is a fundamental and inescapable nessesity, be that in extremely low quantities or high quantities depending on the set up.

There have been arguments raging both for and against water changes for years, and to be honest, in all the posts and litterature ive read, about the only logical reasoning for not doing waer changes is that commercial salts are fundamentally flawed and bare only a passing resemblence to natural sea water. Just about any salt will have varying levels of heavy metals and other elements that may be either in exess or below natural levels. the argument is that doing water changes can increase these levels over time with only minor utilisation by the fauna or system as a whole therby shortening the life of the system. The trouble with this argument though is that its based on two premises, that the salt is the only pathway in for these materials and that a system can run indeffinately. The truth of the matter is that no system can run indeffinately without external influance. Unlike mother nature, the closed system is depived of two major factors. diversity to utilise all aspects of the elemental table and fully cycle all pathways be they benificial or harmfull accumulations, and dispertion or dilution capacity which keeps local changes to chemistry and biological function stable on a large time scale. the other mistake is that food is commonly forgotten as an import route for many substances both desirable and undesirable. All marine organisms adopt part of the chemical makeup of their surroundings into thier body mass as they grow. (the shellfish and Mercury syndrome)..the accumulations might be minute on an elemental level per individual but they are still there none the less if you factor in the many food types we feed, especially algaes which have a huge capacity for trace element assimilation. The question would then be, just how much of this stuff do you add to a tank over the course of its life that isnt taken up by he animals you are feeding...Is it not fair to assume that 5 or 10 years down the line, you have actually added more than your favorite salt has in it?..in which case, by doing water changes 'even small ones' you are actually diluting accumulating levels rather than adding to them therby maintaing the balancing act for a longer period.

Regards

si.

[lindsay]

Agree ,knowing how much and how often can become the hard part especially if the time period between water changes has got longer and longer .

[Simon Garratt]

look above Linds...ive just done an edit....