The effect of PO4 on 'KH'

Thanks Happy, I figured I'd post her as we continue this discussion instead of doing it via PM. that way others can benefit from my ignornce as well.

My tap water is 2-3 (depending on the given week) degrees KH. the PO4 is always 2ppm or maybe a little higher. the test kit jumps from 2-5 and the color range is arbitrary. either way PO4 is at or above 2 from the tap. I have been trying to adjust water before it goes into my tank to keep it at or above 4 KH. I picked that number for my own sanity. I don't like walking the line when I'm gone 3+ days a week. I recently have tried to switch over from baking soda to crushed coral in order to up the calcium for my snails. I prep my water usually for a week in a rubbermaid trash can. the water is circulated via an airstone and also heated. I bagged 10 pounds of crushed coral and put it in the can in line with and above the airstone. It makes little or no measurable difference in a week. So I accepted the fact that crushed coral was slower than that (maybe I'm wrong) and purchased some dolomitic CaCo3 from Gregg watson. I am adding it to the change water at the beggining of the week but it still does not dissolve at a quick rate, and therefore makes little difference in a week.

Now to the tanks. In one utility tank (10 g) I added 5 tablespoons of crushed coral to the substrate (Rfug set up) this tank will stay steady through the week. the other two tanks drop from 4 (after baking soda water change ) to 3 or less by the end of the week. If I miss a water change which I did 3 weeks ago. Kh plummets to 0-1 degree in the 2 week period. I have added crushed coral to the two tanks that didn't already have it. 1 tblspoon in the filter of the 15 g and 2 cups in the filter of the 115g. after afull week they still hang at 3 and have not raised noticeably, however they aren't dropping as quickly as they seemed to before

PO4 was the part of this situation I didn't figure on. my tap po4 is 2+ as mentioned, in the course of a week the po4 drops from almost 2 after a water change to less than 1 ppm in the tank. I assume the plants are using it which is a good thing. So now I'm thinking the coral may be helping a bit since the drop isn't as pronounced as it was before the coral, and the po4 is still dropping
Tell me if I have it straight, any tips, thoughts or corrections would be greatly appreciated as always.
dave

You'll have to bear with me a bit because the tanks are all three at different levels, but there are some similarities.

Tap water kh is 2-3, Ph is between 7.6 and 7.8 depending on Kh (that's after a minimum of 24 hours to equalize) straight from the tap our water is a perfect 7.0.

tank #1. 115 g did not start adding co2 untill 3 weeks ago. Before Co2 addition, co2 stayed at about 6-7 ppm with all surface agitation stopped.
after co2 addition, it stays between 10 and 19 ppm day to day. the increase in plant growth( since co2) also shows a bigger decrease in po4 (makes sense to me) and the difficulty in keeping the the kh high has seemed to speed up a bit since Co2 was added. but not a huge amount. thus I added the coral to the filter to try to counteract it a bit.

Tank #2 15g guppy/ snail breeder. This is the heavily heavily planted tank right now. nitrates stay up around 20 most of the time due to high bio load. I have been dosing with excell for several months, and recently (last week ) started adding co2. plant growth has picked up a little in the week but not a lot yet (too soon I think) I decided to switcvh from excell to co2 because I'm not home to liquid dose on a regular enough basis. This tank runs co2 higher than I really want it too and pushes the 25 ppm limit every night, maybe a little higher ( still working on taming the diy co2 to this small volume). this tank shows no major difference in KH drops from the big tank though. and likewise with po4. however this tank due to the bioload and intensity of the operation gets very large volume changes once or twice a week. usually 70-80 percent at a time. with the large volume changes it is harder to track what's actually happening during the week. when I missed a water change a few weeks ago both this tank and the big one went to 0 (or almost) in a two week period. fortunately the co2 also ran out on the big tank and wasn't installed yet on this tank so I didn't nuke anything.

tank #3 just for reference has a light fish and snail load, a light plant load, it is the tank with the coral in the substrate. It gets a teaspoon of excell on any day when I am home usually averages four dosings a week with excell. the po4 doesn't drop as rapidly. and the KH stays at 4 degrees steady in this tank.

For your reference,here are my filtration specs and media:
tank #1. 115 g has OERFUG with 4x 1140 powerheads (rated output 300 gph) with intake sponges. Ac500 full of sponges, added coral to AC 500 recently. Emporer 400 with sponges in the media well. this tank does have 5 peices of driftwood but they have all been in the tank since it was set in march. The pleco does eat a huge amount of driftwood, and leaves sawdust pleco poop everywhere, but I don't know if the constant exposure of neww wood to the water and his processing of wood have any effect. At a glance I would say the pleco and the wood are a moot point in this, but never discount a detail so I'm adding it.

tank #2 15g guppy tank. OERFUG with 1 550 powerhead (145 gph rating) intake sponge. also has a pengiun 125 with intake sponge and sponges in the media well. I added 1 tblsp coral to this filter almost 2 weeks ago. one small peice of driftwood, nothing eating the wood surface in this tank.

tank #3. 10 g OERFUG with 55 powerhead, and intake sponge, Ac 150 set at low flow with sponges in the well. this tank has the coral mixed in the substrate, also this tank stays steady but there isn't mush going on in there excet snail reproduction. this tank also has one peice of driftwood.

No peat in use, no AC in use. only coral and sponges and pleco poop if it matters.

Sounds right, but I'm pretty tired right now. Spent all day trying to troubleshoot a spreadsheet, a personal hell of my own making

Click to expand...

Gotta love self inflicted pain. I'm self taught on spreadsheets (like most things) and every once in a while I design a self attacking monster. As for this thread, there is no hurry on getting answers for me. every thing is fairly nuke proofed right now in the tanks, and I taught my son to calculate Co2 levels so I can call if I get worried, and I am not near my tanks at the moment
but will be home tomorrow night to tinker until Monday again.
Dave

Hi. I hope I can maybe give you some info as we are in the same area and using the same water supplier.

In my 20g tank with DIY CO2 my PH stays around 6.7-6.8 and kH is at 4. I'm doing a 25% water change each week and after I change the water, my kH drops to 3 and then slowly rises back up to 4 over 24 hours. My tank is fairly heavy planted and a piece of bogwood. I also have a rock, about 5 pounds in weight. Not sure what kind it is (black and white bands, metamorphic?) or whether it affects my kH but I would presume it should be inert. I bought it from Jacks Aquarium so make your own mind up on that one.

I know the DIY CO2 affects the PH because it was neutral before I hooked it up. I add 1ml of Flourish during each water change. Fish load is

6 black skirt tetras
3 paleatus corydoras
1 clown plec
2 ottos

Water parameters are

ammonia 0
nitrite 0
nitrate 10-15
gH 9
kH 4

Unfortunately, I don't have a test for PO4, but might have to check that out now I'm curious.

The black and white rock from Jacks is quartsite laced granite, I have a couple chunks of it as well (awesome looking rock BTW). it isn't raising your Kh but something else is somehow. Since you are in Hilliard you are on the Dublin water treatment system, and should have exactly the same water I get (four treatment plants in columbus with slight variations) everything on the west side is fed from dublin. Is there any coral or shells or limestone in the tank. It sounds like you have have the precise problem I need. You are changing less water, but if your Kh is rising to four. life is good.
the 7.0 you get out of the tap will be 7.6-7.8 in the morning, the co2 will take it back down as you have stated. It seems that columbus regulate their co2 to creat neutral tap water at all of the plants.
dave

There's nothing else in my tank. About the only other info I can give is my filter is a Fluval 204. I have a layer of pre-filter and two layers of bio-max. My CO2 mix is a 1/4 tsp yeast, 1 tsp baking soda and 4 cups sugar. Lighting is 2.25 wpg.

Substrate is natural gravel although several years ago it was colored gravel. I've managed to remove most of it but a few chips are still there (bits of pink in the picture).

That pretty much sums up my whole setup. I wouldn't win any prizes for my tank but I kind of like the chaotic look.

Well the chaotic look seems good in the picture
Any thoguhts Happychem? I may run by jacks and see if they are selling something different these days. Rocks I can figure out, fish I still wonder a lot about.
dave

Dave, my PO4 is just a shade over 1ppm.