my ph in my tank is droping and i dont know why

[verynewatthis]

my tank runs at 8.2,,,,,24/7....i run a swamp cooler all day and night. so new air is always coming in to my house. when i do a water change i lose about a tenth. but it comes back up in a few hrs or so...i do run a c02 reactor but the co is turned way down.....one bubble every 8 to 10 secs....so i dont think it is that...i added some cal a few days ago but i only lost a tenth or so back then....is there a safe way to get my ph up?....i dont want to add a bunch of soda cuz my alk is at ten and that is where i want it to stay..i normaly dont get all worked up but my ph is at 7.7 right now...and yes i did check my ph monitor and it is working fine....any help would be great...thz...rich hancock

[GaryP]

Dripping Kalk may be the best solution. The natural tendency is for your pH to fall with time unless corrected. A lot of people find their pH falls when using a calcium reactor because of excess CO2 left over from the reactor.

Your only other solution is to add washing soda but that will bring up your alkalinity too.

[NaCl_H2O]

...and yes i did check my ph monitor and it is working fine

Do you mean that you calibrated it? They can "drift" significantly!

[verynewatthis]

yes i did a calibration check on it...the monitor is only a month old or so...but test great...rich...
ps...could to much water evaporation with a auto top off make this happen...cuz i have a big fan on the tank now..... and i lose a lot of water a week...its a 80 gal tank...and lose over ten gallons each week...any thoughts???

[matt]

Your calcium reactor might be out of adjustment. Make sure your effluent has a dkh of at least 20; you'll need a salifert or other high quality test kit. Use the low resolution setting, where you double the results; this will keep it on the scale. Sometimes you need to lower the reactor ph, by increasing the CO2, to keep the tank pk stable. You should also shoot for a slow drip of lower ph effluent rather than a faster drip of higher ph effluent. It's a little counter intuitive, but it really works. First, check the effluent dkh, if it's 20 or above (higher is better) you're okay. But if it's lower, crank up the CO2 and keep the drip really slow. When I dropped my reactor ph from 6.9 to 6.6, my tank ph went up. I was also able to slow down the effluent drip a little and keep up with calcium demand.

BTW, 8.2 is terrific ph for a tank running a calcium reactor. If it was stable at that for a while and then dropped quickly to 7.7, a couple of possible things come to mind, but they're only guesses. If you got that reading early in the morning after the lights had been out all night, it's probably not something to really worry about, unless it's an indication that something's up with your water quality. First thing I'd look into is dissolved organics; you might try an ORP test. High dissolved organics and low ORP tend to go together. High DOC usually lowers ph a little.

If it's a light cycle issue, you could address it by setting up a well lit refugium on a reverse cycle with caulerpa growing; that'll use up CO2 at night. If I had to guess, though, you probably just have to get your reactor better dialed in.

Evaporating 10 gallons/week on an 80 gallon tank is pretty low evaporation IMO. My old 45 breeder evaporated 2.5 gallons/day, and my 110 almost double that. But that's pretty high; I had fans on the sump to keep the temp down. The only way this might tie into your ph issue is that it's an indication that maybe you don't strong water movement with lots of air/water exchange, which will make your tank more likely to drop in ph. Again, that's a guess.

As Gary said, dripping some kalk, especially at night, will certainly raise your ph; it'sll also raise your dkh somewhat, but that's not a problem unless you can't keep your calcium up.

You can avoid the ph drop at water change time by really aerating the replacement salt water in a tub for a few days to raise it's ph.

[verynewatthis]

okay i tested the alk coming out of my reactor and it tested at 11 ish dkh ...so i turned the output down to a drip and turned up the co2..i will check it in the morning and see what happens...

[matt]

If you were shooting a stream of reactor effluent into an 80 gallon tank, that's probably the reason for your ph drop.

Just as a rough guess, go for these numbers as a starting point.
effluent ph 6.6-7
effluent dkh 25-30
effluent flow 50-75ml/min

To measure the flow, just collect your effluent in a shot glass or test tube (whatever you have around) for 15 secs, then you can use a salifert syringe to measure what you got, multiply X4. I wouldn't go over 100ml/min. A stream is probably more like 500 (just a guess)

Where you go from those numbers depends on your calcium demand. You want the dkh to remain high, and think of the effluent flow and CO2(reactor ph) as being balanced at a given dkh. More flow, same CO2, results in lower dkh. Less flow, same CO2, higher dkh. (within a range) So if you need more calcium and carbonate to keep your tank happy, you can increase the CO2 and flow a little; keeping the effluent ph and dkh steady. It takes a few tries and some patience. If you only need a little more, you could try turning up the CO2 without increasing the flow; this lowers the ph and raises the dkh. But I would not run a ph lower than 6.5, although I bet some people do with no problem.

Just so you know, the reason flow has so much to do with effluent dkh is because the effluent flow is directly responsible for the contact time in the reactor. Double the effluent flow at a given reactor volume is half the contact time. How much of an impact this has on the dissolution of calcium carbonate in the reactor I don't know, but it's got to be pretty significant. This is why I like big calcium reactors with strong internal circulation. Obviously, reactor capacity has exactly the same effect; double the volvume, double the contact time at a given flow rate.

[GaryP]

There you go Rich. Matt is the man when it comes to reactors and tuning them.

[verynewatthis]

sorry i forgot to sign in...rich

[matt]

For now, maybe you should shut off the reactor flow altogether. Then go to the grocery store and get some pickling lime; make sure it says 100% hydrated lime. Dissolve a couple of tablespoons/gallon of R.O. water, let it settle, and drip that into your tank. Pickling lime is the same as kalkwasser mix.

7.5 in the middle of the day is real low. If your dkh is really 10 and you have strong aeration and water flow, and a ph of 7.5, something's wrong. Unless there are obvious signs of trouble like corals retracting, the 1st thing I'd suspect is a faulty ph reading. If you don't have a skimmer going, now would be a good time to get a hold of one. If you have a sump, you might try the urchin pro, or remora pro if you need a hang-on type. Personally, I'm not really too fond of aquaC skimmers, but I'm a skimmer snob and lots of people love them; plus you could get one right away, plug it in, and it needs basically no adjustment.

[verynewatthis]

well ill go and see if my store has some lime...as far as the monitor . it is good. it is very new, and i did a cal test and it checks out..and i do run a euro reef skimmer, and i use salifert test kits. so i know all readings are right...well ill turn off the reactor when i get off work today...ill keep ya ll up to date...thz rich

[verynewatthis]

okay where do i go to get " pickling lime; 100% hydrated lime"...rich

[verynewatthis]

i found problem. it was the ph monitor....stupid thing.....thz everyone... Matt i might get rid of mine too...thz again everyone...rich

[matt]

I found the hand held ph probe (Hannah mini-checker, I think) to be a good reliable way of checking ph. I calibrated it each time I used it, with 7 and 10 fluid. I had to remove a sample from the tank in a shot glass to be accurate.

I'm glad the problem wasn't with your tank, only the probe. You still might want to set up your reactor the way I described. It'll work better.

Good luck!
Matt

[verynewatthis]

ya matt im doing what you said...but i have to wait to get the readings right...ill let yall know how it gose...thz again..rich